package org.apache.maven.doxia.module.docbook;
   
   /*
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF licenses this file
    * to you under the Apache License, Version 2.0 (the
    * "License"); you may not use this file except in compliance
   * with the License.  You may obtain a copy of the License at
   *
   *   http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing,
   * software distributed under the License is distributed on an
   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
   * KIND, either express or implied.  See the License for the
   * specific language governing permissions and limitations
   * under the License.
   */
  
  import java.io.PrintWriter;
  import java.io.StringWriter;
  import java.io.Writer;
  import java.util.ArrayList;
  import java.util.HashMap;
  import java.util.List;
  import java.util.Locale;
  import java.util.Map;
  import java.util.Set;
  import java.util.Stack;
  import java.util.StringTokenizer;
  import java.util.TreeSet;
  
  import javax.swing.text.MutableAttributeSet;
  import javax.swing.text.SimpleAttributeSet;
  
  import org.apache.maven.doxia.sink.Sink;
  import org.apache.maven.doxia.sink.SinkEventAttributes;
  import org.apache.maven.doxia.sink.impl.AbstractXmlSink;
  import org.apache.maven.doxia.sink.impl.SinkEventAttributeSet;
  import org.apache.maven.doxia.util.DoxiaUtils;
  import org.codehaus.plexus.util.FileUtils;
  
  import static org.apache.maven.doxia.util.HtmlTools.escapeHTML;
  
  /**
   * <a href="http://www.oasis-open.org/docbook">Docbook</a> Sink implementation.
   * <br>
   * It uses the Docbook v4.4 DTD <a href="http://www.oasis-open.org/docbook/sgml/4.4/docbookx.dtd">
   * http://www.oasis-open.org/docbook/sgml/4.4/docbookx.dtd</a>.
   *
   * @since 1.0
   */
  public class DocBookSink
      extends AbstractXmlSink
      implements DocbookMarkup, SimplifiedDocbookMarkup
  {
      /** DocBook V4.4 SGML public id: "-//OASIS//DTD DocBook V4.4//EN"
       * @deprecated since 1.1, use {@link DocbookMarkup#DEFAULT_SGML_PUBLIC_ID} instead of. */
      public static final String DEFAULT_SGML_PUBLIC_ID = DocbookMarkup.DEFAULT_SGML_PUBLIC_ID;
  
      /** DocBook XML V4.4 XML public id: "-//OASIS//DTD DocBook XML V4.4//EN"
       * @deprecated since 1.1, use {@link DocbookMarkup#DEFAULT_XML_PUBLIC_ID} instead of. */
      public static final String DEFAULT_XML_PUBLIC_ID = DocbookMarkup.DEFAULT_XML_PUBLIC_ID;
  
      /** DocBook XML V4.4 XML system id: "http://www.oasis-open.org/docbook/xml/4.4/docbookx.dtd"
       * @deprecated since 1.1, use {@link DocbookMarkup#DEFAULT_XML_SYSTEM_ID} instead of. */
      public static final String DEFAULT_XML_SYSTEM_ID = DocbookMarkup.DEFAULT_XML_SYSTEM_ID;
  
      /** DocBook XML V4.4 SGML system id: "http://www.oasis-open.org/docbook/xml/4.4/docbookx.dtd"
       * @deprecated since 1.1, use {@link DocbookMarkup#DEFAULT_SGML_SYSTEM_ID} instead of. */
      public static final String DEFAULT_SGML_SYSTEM_ID = DocbookMarkup.DEFAULT_SGML_SYSTEM_ID;
  
      /** The output writer. */
      private PrintWriter out;
  
      /** xmlMode. */
      private boolean xmlMode = false;
  
      /** styleSheet. */
      private String styleSheet = null;
  
      /** language. */
      private String lang = null;
  
      /** publicId. */
      private String publicId = null;
  
      /** systemId. */
      private String systemId = null;
  
      /** italicBegin. */
      private String italicBeginTag;
  
      /** italicEnd. */
      private String italicEndTag;
  
      /** boldBegin. */
     private String boldBeginTag;
 
     /** boldEnd. */
     private String boldEndTag;
 
     /** monospacedBegin. */
     private String monospacedBeginTag;
 
     /** monospacedEnd. */
     private String monospacedEndTag;
 
     /** horizontalRule. */
     private String horizontalRuleElement;
 
     /** pageBreak. */
     private String pageBreakElement;
 
     /** lineBreak. */
     private String lineBreakElement;
 
     /** An image source file. */
     private String graphicsFileName;
 
     /** hasTitle. */
     private boolean hasTitle;
 
     /** authorDate. */
     private boolean authorDateFlag;
 
     /** verbatim. */
     private boolean verbatimFlag;
 
     /** externalLink. */
     private boolean externalLinkFlag;
 
     /** tableHasCaption. */
     private boolean tableHasCaption;
 
     /** Used for table rows. */
     private PrintWriter savedOut;
 
     /** tableRows. */
     private String tableRows;
 
     /** tableRows writer. */
     private StringWriter tableRowsWriter;
 
     /** tableHasGrid. */
     private boolean tableHasGrid;
 
     private boolean skip;
 
     private boolean paragraph;
 
     private String encoding;
 
     /** Keep track of the closing tags for inline events. */
     protected Stack<List<String>> inlineStack = new Stack<>();
 
     /** Map of warn messages with a String as key to describe the error type and a Set as value.
      * Using to reduce warn messages. */
     private Map<String, Set<String>> warnMessages;
 
     /**
      * Constructor, initialize the Writer.
      *
      * @param writer not null writer to write the result. <b>Should</b> be an UTF-8 Writer.
      * You could use <code>newXmlWriter</code> methods from {@link org.codehaus.plexus.util.WriterFactory}.
      */
     protected DocBookSink( Writer writer )
     {
         this( writer, null );
     }
 
     /**
      * Constructor, initialize the Writer and tells which encoding is used.
      *
      * @param writer not null writer to write the result.
      * @param encoding the encoding used, that should be written to the generated HTML content
      * if not <code>null</code>.
      */
     protected DocBookSink( Writer writer, String encoding )
     {
         this.out = new PrintWriter( writer );
         this.encoding = encoding;
 
         setItalicElement( "<emphasis>" );
         setBoldElement( "<emphasis role=\"bold\">" );
         setMonospacedElement( "<literal>" );
         setHorizontalRuleElement( "<!-- HR -->" );
         setPageBreakElement( "<!-- PB -->" );
         setLineBreakElement( "<!-- LB -->" );
     }
 
     /**
      * Constructor, initialize the Writer and tells which encoding and languageId are used.
      *
      * @param writer not null writer to write the result.
      * @param encoding the encoding used, that should be written to the generated HTML content
      * if not <code>null</code>.
      * @param languageId language identifier for the root element as defined by
      * <a href="ftp://ftp.isi.edu/in-notes/bcp/bcp47.txt">IETF BCP 47</a>, Tags for the Identification of Languages;
      * in addition, the empty string may be specified.
      * @since 1.1
      */
     protected DocBookSink( Writer writer, String encoding, String languageId )
     {
         this( writer, encoding );
 
         this.lang = languageId;
     }
 
     /**
      * <p>escapeSGML</p>
      *
      * @param text The text to escape.
      * @param xmlMode xmlMode.
      * @return The escaped text.
      * @deprecated Use HtmlTools#escapeHTML(String,boolean).
      */
     public static String escapeSGML( String text, boolean xmlMode )
     {
         return escapeHTML( text, xmlMode );
     }
 
     /**
      * Sets the xml mode.
      *
      * @param mode the mode to set.
      * @deprecated xml mode is not used.
      */
     public void setXMLMode( boolean mode )
     {
         this.xmlMode = mode;
     }
 
     /**
      * Returns the current xmlMode.
      *
      * @return the current xmlMode.
      * @deprecated xml mode is not used.
      */
     public boolean isXMLMode()
     {
         return xmlMode;
     }
 
     /**
      * Sets the encoding. The encoding specified here must be consistent with then encoding
      * used in the Writer used by this DocBookSink instance.
      *
      * @param enc the encoding to set.
      */
     public void setEncoding( String enc )
     {
         encoding = enc;
     }
 
     /**
      * Returns the encoding.
      *
      * @return the encoding set (can be <code>null</code>).
      */
     public String getEncoding()
     {
         return encoding;
     }
 
     /**
      * Sets the styleSheet.
      *
      * @param sheet the styleSheet to set.
      */
     public void setStyleSheet( String sheet )
     {
         this.styleSheet = sheet;
     }
 
     /**
      * Returns the current styleSheet.
      *
      * @return the current styleSheet.
      */
     public String getStyleSheet()
     {
         return styleSheet;
     }
 
     /**
      * Sets the publicId.
      *
      * @param id the publicId to set.
      */
     public void setPublicId( String id )
     {
         this.publicId = id;
     }
 
     /**
      * Returns the current publicId.
      *
      * @return the current publicId.
      */
     public String getPublicId()
     {
         return publicId;
     }
 
     /**
      * Sets the systemId.
      *
      * @param id the systemId to set.
      */
     public void setSystemId( String id )
     {
         this.systemId = id;
     }
 
     /**
      * Returns the current systemId.
      *
      * @return the current systemId.
      */
     public String getSystemId()
     {
         return systemId;
     }
 
     /**
      * Sets the language.
      *
      * @param language the language to set.
      */
     public void setLanguage( String language )
     {
         this.lang = language;
     }
 
     /**
      * Returns the current language.
      *
      * @return the current language.
      */
     public String getLanguage()
     {
         return lang;
     }
 
     /**
      * Sets the current italicBeginTag and constructs the corresponding end tag from it.
      *
      * @param tag the tag to set. If tag is null, the empty string is used.
      */
     public void setItalicElement( String tag )
     {
         if ( tag == null )
         {
             tag = "";
         }
         this.italicBeginTag = tag;
         italicEndTag = makeEndTag( italicBeginTag );
     }
 
     /**
      * Constructs the corresponding end tag from the given begin tag.
      *
      * @param beginTag the begin tag to set. If null, the empty string is returned.
      * @return the corresponding end tag.
      */
     private String makeEndTag( String beginTag )
     {
         int length = beginTag.length();
         if ( length == 0 )
         {
             return "";
         }
 
         if ( beginTag.charAt( 0 ) != '<' || beginTag.charAt( length - 1 ) != '>' )
         {
             throw new IllegalArgumentException( "'" + beginTag + "', not a tag" );
         }
 
         StringTokenizer tokens = new StringTokenizer( beginTag, "<> \t\n\r\f" );
         if ( !tokens.hasMoreTokens() )
         {
             throw new IllegalArgumentException( "'" + beginTag + "', invalid tag" );
         }
 
         return "</" + tokens.nextToken() + ">";
     }
 
     /**
      * Returns the current italicBeginTag.
      *
      * @return the current italicBeginTag. Defaults to {@code <emphasis>}.
      */
     public String getItalicElement()
     {
         return italicBeginTag;
     }
 
     /**
      * Sets the current boldBeginTag and constructs the corresponding end tag from it.
      *
      * @param tag the tag to set. If tag is null, the empty string is used.
      */
     public void setBoldElement( String tag )
     {
         if ( tag == null )
         {
             tag = "";
         }
         this.boldBeginTag = tag;
         boldEndTag = makeEndTag( boldBeginTag );
     }
 
     /**
      * Returns the current boldBeginTag.
      *
      * @return the current boldBeginTag. Defaults to {@code <emphasis role=\"bold\">}.
      */
     public String getBoldElement()
     {
         return boldBeginTag;
     }
 
     /**
      * Sets the current monospacedBeginTag and constructs the corresponding end tag from it.
      *
      * @param tag the tag to set. If tag is null, the empty string is used.
      */
     public void setMonospacedElement( String tag )
     {
         if ( tag == null )
         {
             tag = "";
         }
         this.monospacedBeginTag = tag;
         monospacedEndTag = makeEndTag( monospacedBeginTag );
     }
 
     /**
      * Returns the current monospacedBeginTag.
      *
      * @return the current monospacedBeginTag. Defaults to {@code <literal>}.
      */
     public String getMonospacedElement()
     {
         return monospacedBeginTag;
     }
 
     /**
      * Sets the current horizontalRuleElement.
      *
      * @param element the element to set.
      */
     public void setHorizontalRuleElement( String element )
     {
         this.horizontalRuleElement = element;
     }
 
     /**
      * Returns the current horizontalRuleElement.
      *
      * @return the current horizontalRuleElement. Defaults to "<!-- HR -->".
      */
     public String getHorizontalRuleElement()
     {
         return horizontalRuleElement;
     }
 
     /**
      * Sets the current pageBreakElement.
      *
      * @param element the element to set.
      */
     public void setPageBreakElement( String element )
     {
         this.pageBreakElement = element;
     }
 
     /**
      * Returns the current pageBreakElement.
      *
      * @return the current pageBreakElement. Defaults to "<!-- PB -->".
      */
     public String getPageBreakElement()
     {
         return pageBreakElement;
     }
 
     /**
      * Sets the current lineBreakElement.
      *
      * @param element the element to set.
      */
     public void setLineBreakElement( String element )
     {
         this.lineBreakElement = element;
     }
 
     /**
      * Returns the current lineBreakElement.
      *
      * @return the current lineBreakElement. Defaults to "<!-- LB -->".
      */
     public String getLineBreakElement()
     {
         return lineBreakElement;
     }
 
     /**
      * Reset all variables.
      *
      * @deprecated since 1.1.2, use {@link #init()} instead of.
      */
     protected void resetState()
     {
        init();
     }
 
     /**
      * {@inheritDoc}
      */
     protected void init()
     {
         hasTitle = false;
         authorDateFlag = false;
         verbatimFlag = false;
         externalLinkFlag = false;
         graphicsFileName = null;
         tableHasCaption = false;
         savedOut = null;
         tableRows = null;
         tableHasGrid = false;
     }
 
     // ----------------------------------------------------------------------
     //
     // ----------------------------------------------------------------------
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#DEFAULT_XML_PUBLIC_ID
      * @see SimplifiedDocbookMarkup#DEFAULT_XML_SYSTEM_ID
      * @see SimplifiedDocbookMarkup#ARTICLE_TAG
      */
     public void head()
     {
         init();
 
         MutableAttributeSet att = writeXmlHeader( "article" );
 
         writeStartTag( SimplifiedDocbookMarkup.ARTICLE_TAG, att );
     }
 
     /**
      * writeXmlHeader.
      *
      * @param root not null.
      * @return an attribute set.
      * @see SimplifiedDocbookMarkup#DEFAULT_XML_PUBLIC_ID
      * @see SimplifiedDocbookMarkup#DEFAULT_XML_SYSTEM_ID
      * @see SimplifiedDocbookMarkup#ARTICLE_TAG
      * @since 1.1
      */
     protected MutableAttributeSet writeXmlHeader( String root )
     {
         markup( "<?xml version=\"1.0\"" );
         if ( encoding != null )
         {
             markup( " encoding=\"" + encoding + "\"" );
         }
         markup( "?>" );
 
         if ( styleSheet != null )
         {
             markup( "<?xml-stylesheet type=\"text/css\" href=\"" + styleSheet + "\" ?>" );
         }
 
         String pubId;
         markup( "<!DOCTYPE " + root + " PUBLIC" );
 
         if ( publicId == null )
         {
             pubId = SimplifiedDocbookMarkup.DEFAULT_XML_PUBLIC_ID;
         }
         else
         {
             pubId = publicId;
         }
         markup( " \"" + pubId + "\"" );
         String sysId = systemId;
         if ( sysId == null )
         {
                 sysId = SimplifiedDocbookMarkup.DEFAULT_XML_SYSTEM_ID;
         }
         markup( " \"" + sysId + "\">" );
 
         MutableAttributeSet att = new SimpleAttributeSet();
         if ( lang != null )
         {
             att.addAttribute( LANG_ATTRIBUTE, lang );
         }
         return att;
     }
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#ARTICLEINFO_TAG
      */
     public void head_()
     {
         if ( hasTitle )
         {
             writeEndTag( SimplifiedDocbookMarkup.ARTICLEINFO_TAG );
             hasTitle = false;
         }
     }
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#ARTICLEINFO_TAG
      * @see SimplifiedDocbookMarkup#TITLE_TAG
      */
     public void title()
     {
         writeStartTag( SimplifiedDocbookMarkup.ARTICLEINFO_TAG );
         writeStartTag( SimplifiedDocbookMarkup.TITLE_TAG );
         hasTitle = true;
     }
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#TITLE_TAG
      */
     public void title_()
     {
         writeEndTag( SimplifiedDocbookMarkup.TITLE_TAG );
     }
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#CORPAUTHOR_TAG
      */
     public void author()
     {
         authorDateFlag = true;
         writeStartTag( SimplifiedDocbookMarkup.CORPAUTHOR_TAG );
     }
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#CORPAUTHOR_TAG
      */
     public void author_()
     {
         writeEndTag( SimplifiedDocbookMarkup.CORPAUTHOR_TAG );
         authorDateFlag = false;
     }
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#DATE_TAG
      */
     public void date()
     {
         authorDateFlag = true;
         writeStartTag( SimplifiedDocbookMarkup.DATE_TAG );
     }
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#DATE_TAG
      */
     public void date_()
     {
         writeEndTag( SimplifiedDocbookMarkup.DATE_TAG );
         authorDateFlag = false;
     }
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#ARTICLE_TAG
      */
     public void body_()
     {
         writeEndTag( SimplifiedDocbookMarkup.ARTICLE_TAG );
         out.flush();
         init();
     }
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#SIDEBAR_TAG
      */
     public void sidebar()
     {
         writeStartTag( SimplifiedDocbookMarkup.SIDEBAR_TAG );
     }
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#SIDEBAR_TAG
      */
     public void sidebar_()
     {
         writeEndTag( SimplifiedDocbookMarkup.SIDEBAR_TAG );
     }
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#SECTION_TAG
      */
     public void section1()
     {
         writeStartTag( SimplifiedDocbookMarkup.SECTION_TAG );
     }
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#SECTION_TAG
      */
     public void section1_()
     {
         writeEndTag( SimplifiedDocbookMarkup.SECTION_TAG );
     }
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#SECTION_TAG
      */
     public void section2()
     {
         writeStartTag( SimplifiedDocbookMarkup.SECTION_TAG );
     }
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#SECTION_TAG
      */
     public void section2_()
     {
         writeEndTag( SimplifiedDocbookMarkup.SECTION_TAG );
     }
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#SECTION_TAG
      */
     public void section3()
     {
         writeStartTag( SimplifiedDocbookMarkup.SECTION_TAG );
     }
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#SECTION_TAG
      */
     public void section3_()
     {
         writeEndTag( SimplifiedDocbookMarkup.SECTION_TAG );
     }
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#SECTION_TAG
      */
     public void section4()
     {
         writeStartTag( SimplifiedDocbookMarkup.SECTION_TAG );
     }
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#SECTION_TAG
      */
     public void section4_()
     {
         writeEndTag( SimplifiedDocbookMarkup.SECTION_TAG );
     }
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#SECTION_TAG
      */
     public void section5()
     {
         writeStartTag( SimplifiedDocbookMarkup.SECTION_TAG );
     }
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#SECTION_TAG
      */
     public void section5_()
     {
         writeEndTag( SimplifiedDocbookMarkup.SECTION_TAG );
     }
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#TITLE_TAG
      */
     public void sectionTitle()
     {
         writeStartTag( SimplifiedDocbookMarkup.TITLE_TAG );
     }
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#TITLE_TAG
      */
     public void sectionTitle_()
     {
         writeEndTag( SimplifiedDocbookMarkup.TITLE_TAG );
     }
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#TITLE_TAG
      */
     public void sectionTitle1()
     {
         writeStartTag( SimplifiedDocbookMarkup.TITLE_TAG );
     }
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#TITLE_TAG
      */
     public void sectionTitle1_()
     {
         writeEndTag( SimplifiedDocbookMarkup.TITLE_TAG );
     }
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#TITLE_TAG
      */
     public void sectionTitle2()
     {
         writeStartTag( SimplifiedDocbookMarkup.TITLE_TAG );
     }
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#TITLE_TAG
      */
     public void sectionTitle2_()
     {
         writeEndTag( SimplifiedDocbookMarkup.TITLE_TAG );
     }
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#TITLE_TAG
      */
     public void sectionTitle3()
     {
         writeStartTag( SimplifiedDocbookMarkup.TITLE_TAG );
     }
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#TITLE_TAG
      */
     public void sectionTitle3_()
     {
         writeEndTag( SimplifiedDocbookMarkup.TITLE_TAG );
     }
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#TITLE_TAG
      */
     public void sectionTitle4()
     {
         writeStartTag( SimplifiedDocbookMarkup.TITLE_TAG );
     }
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#TITLE_TAG
      */
     public void sectionTitle4_()
     {
         writeEndTag( SimplifiedDocbookMarkup.TITLE_TAG );
     }
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#TITLE_TAG
      */
     public void sectionTitle5()
     {
         writeStartTag( SimplifiedDocbookMarkup.TITLE_TAG );
     }
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#TITLE_TAG
      */
     public void sectionTitle5_()
     {
         writeEndTag( SimplifiedDocbookMarkup.TITLE_TAG );
     }
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#SECTIONINFO_TAG
      */
     public void header()
     {
         writeStartTag( SimplifiedDocbookMarkup.SECTIONINFO_TAG );
     }
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#SECTIONINFO_TAG
      */
     public void header_()
     {
         writeEndTag( SimplifiedDocbookMarkup.SECTIONINFO_TAG );
     }
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#ITEMIZEDLIST_TAG
      */
     public void list()
     {
         paragraph_();
         writeStartTag( SimplifiedDocbookMarkup.ITEMIZEDLIST_TAG );
     }
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#ITEMIZEDLIST_TAG
      */
     public void list_()
     {
         writeEndTag( SimplifiedDocbookMarkup.ITEMIZEDLIST_TAG );
     }
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#LISTITEM_TAG
      */
     public void listItem()
     {
         writeStartTag( SimplifiedDocbookMarkup.LISTITEM_TAG );
         paragraph();
     }
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#LISTITEM_TAG
      */
     public void listItem_()
     {
         paragraph_();
         writeEndTag( SimplifiedDocbookMarkup.LISTITEM_TAG );
     }
 
     /**
      * {@inheritDoc}
      * @see SimplifiedDocbookMarkup#ORDEREDLIST_TAG
      * @see SimplifiedDocbookMarkup#NUMERATION_ATTRIBUTE
      */
     public void numberedList( int numbering )
     {
         String numeration = DocbookUtils.docbookListNumbering( numbering );
 
         paragraph_();
 
         MutableAttributeSet att = new SimpleAttributeSet();
         att.addAttribute( SimplifiedDocbookMarkup.NUMERATION_ATTRIBUTE, numeration );
 
         writeStartTag( SimplifiedDocbookMarkup.ORDEREDLIST_TAG, att );
     }
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#ORDEREDLIST_TAG
      */
     public void numberedList_()
     {
         writeEndTag( SimplifiedDocbookMarkup.ORDEREDLIST_TAG );
     }
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#LISTITEM_TAG
      */
     public void numberedListItem()
     {
         writeStartTag( SimplifiedDocbookMarkup.LISTITEM_TAG );
         paragraph();
     }
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#LISTITEM_TAG
      */
     public void numberedListItem_()
     {
         paragraph_();
         writeEndTag( SimplifiedDocbookMarkup.LISTITEM_TAG );
     }
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#VARIABLELIST_TAG
      */
     public void definitionList()
     {
         paragraph_();
         writeStartTag( SimplifiedDocbookMarkup.VARIABLELIST_TAG );
     }
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#VARIABLELIST_TAG
      */
     public void definitionList_()
     {
         writeEndTag( SimplifiedDocbookMarkup.VARIABLELIST_TAG );
     }
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#VARLISTENTRY_TAG
      */
     public void definitionListItem()
     {
         writeStartTag( SimplifiedDocbookMarkup.VARLISTENTRY_TAG );
     }
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#VARLISTENTRY_TAG
      */
     public void definitionListItem_()
     {
         writeEndTag( SimplifiedDocbookMarkup.VARLISTENTRY_TAG );
     }
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#TERM_TAG
      */
     public void definedTerm()
     {
         writeStartTag( SimplifiedDocbookMarkup.TERM_TAG );
     }
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#TERM_TAG
      */
     public void definedTerm_()
     {
         writeEndTag( SimplifiedDocbookMarkup.TERM_TAG );
     }
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#LISTITEM_TAG
      */
     public void definition()
     {
         writeStartTag( SimplifiedDocbookMarkup.LISTITEM_TAG );
         paragraph();
     }
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#LISTITEM_TAG
      */
     public void definition_()
     {
         paragraph_();
         writeEndTag( SimplifiedDocbookMarkup.LISTITEM_TAG );
     }
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#PARA_TAG
      */
     public void paragraph()
     {
         if ( !paragraph )
         {
             writeStartTag( SimplifiedDocbookMarkup.PARA_TAG );
             paragraph = true;
         }
     }
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#PARA_TAG
      */
     public void paragraph_()
     {
         if ( paragraph )
         {
             writeEndTag( SimplifiedDocbookMarkup.PARA_TAG );
             paragraph = false;
         }
     }
 
     /**
      * {@inheritDoc}
      * @see SimplifiedDocbookMarkup#PROGRAMLISTING_TAG
      */
     public void verbatim( boolean boxed )
     {
         verbatimFlag = true;
         paragraph_();
         writeStartTag( SimplifiedDocbookMarkup.PROGRAMLISTING_TAG );
     }
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#PROGRAMLISTING_TAG
      */
     public void verbatim_()
     {
         writeEndTag( SimplifiedDocbookMarkup.PROGRAMLISTING_TAG );
         verbatimFlag = false;
     }
 
     /**
      * {@inheritDoc}
      */
     public void horizontalRule()
     {
         markup( horizontalRuleElement );
     }
 
     /**
      * {@inheritDoc}
      */
     public void pageBreak()
     {
         markup( pageBreakElement );
     }
 
     /**
      * {@inheritDoc}
      */
     public void figure()
     {
         writeStartTag( SimplifiedDocbookMarkup.MEDIAOBJECT_TAG );
     }
 
     /**
      * {@inheritDoc}
      */
     public void figure_()
     {
         writeEndTag( SimplifiedDocbookMarkup.MEDIAOBJECT_TAG );
     }
 
     /**
      * <p>graphicElement</p>
      *
      * @see SimplifiedDocbookMarkup#MEDIAOBJECT_TAG
      * @see SimplifiedDocbookMarkup#IMAGEOBJECT_TAG
      * @see SimplifiedDocbookMarkup#IMAGEDATA_TAG
      * @see SimplifiedDocbookMarkup#FORMAT_ATTRIBUTE
      * @see SimplifiedDocbookMarkup#FILEREF_ATTRIBUTE
      * @deprecated do not use!
      */
     protected void graphicElement()
     {
         if ( graphicsFileName != null )
         {
             String format = FileUtils.extension( graphicsFileName ).toUpperCase( Locale.ENGLISH );
             if ( format.length() == 0 )
             {
                 format = "JPEG";
             }
 
             writeStartTag( SimplifiedDocbookMarkup.MEDIAOBJECT_TAG );
             writeStartTag( SimplifiedDocbookMarkup.IMAGEOBJECT_TAG );
 
             MutableAttributeSet att = new SimpleAttributeSet();
             att.addAttribute( SimplifiedDocbookMarkup.FORMAT_ATTRIBUTE, escapeHTML( format, true ) );
             att.addAttribute( SimplifiedDocbookMarkup.FILEREF_ATTRIBUTE, escapeHTML( graphicsFileName, true ) );
 
             writeSimpleTag( SimplifiedDocbookMarkup.IMAGEDATA_TAG, att );
 
             writeEndTag( SimplifiedDocbookMarkup.IMAGEOBJECT_TAG );
             writeEndTag( SimplifiedDocbookMarkup.MEDIAOBJECT_TAG );
             graphicsFileName = null;
         }
     }
 
     /** {@inheritDoc} */
     public void figureGraphics( String name )
     {
         String format = FileUtils.extension( name ).toUpperCase( Locale.ENGLISH );
 
         writeStartTag( SimplifiedDocbookMarkup.IMAGEOBJECT_TAG );
 
         MutableAttributeSet att = new SimpleAttributeSet();
         att.addAttribute( SimplifiedDocbookMarkup.FORMAT_ATTRIBUTE, escapeHTML( format, true ) );
         att.addAttribute( SimplifiedDocbookMarkup.FILEREF_ATTRIBUTE, escapeHTML( name, true ) );
 
         writeSimpleTag( SimplifiedDocbookMarkup.IMAGEDATA_TAG, att );
 
         writeEndTag( SimplifiedDocbookMarkup.IMAGEOBJECT_TAG );
     }
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#FIGURE_TAG
      * @see SimplifiedDocbookMarkup#TITLE_TAG
      */
     public void figureCaption()
     {
         writeStartTag( SimplifiedDocbookMarkup.CAPTION_TAG );
         writeStartTag( SimplifiedDocbookMarkup.PARA_TAG );
     }
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#FIGURE_TAG
      * @see SimplifiedDocbookMarkup#TITLE_TAG
      */
     public void figureCaption_()
     {
         writeEndTag( SimplifiedDocbookMarkup.PARA_TAG );
         writeEndTag( SimplifiedDocbookMarkup.CAPTION_TAG );
     }
 
     /**
      * {@inheritDoc}
      */
     public void table()
     {
         tableHasCaption = false;
     }
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#INFORMALTABLE_TAG
      * @see SimplifiedDocbookMarkup#FRAME_ATTRIBUTE
      * @see SimplifiedDocbookMarkup#ROWSEP_ATTRIBUTE
      * @see SimplifiedDocbookMarkup#COLSEP_ATTRIBUTE
      * @see SimplifiedDocbookMarkup#TABLE_TAG
      */
     public void table_()
     {
         if ( tableHasCaption )
         {
             tableHasCaption = false;
             // Formal table+title already written to original destination ---
 
             out.write( tableRows  );
             writeEndTag( TABLE_TAG );
         }
         else
         {
             String frame = "none";
             String sep = "0";
             if ( tableHasGrid )
             {
                 frame = "all";
                 sep = "1";
             }
 
             MutableAttributeSet att = new SimpleAttributeSet();
             att.addAttribute( SimplifiedDocbookMarkup.FRAME_ATTRIBUTE, frame );
             att.addAttribute( SimplifiedDocbookMarkup.ROWSEP_ATTRIBUTE, sep );
             att.addAttribute( SimplifiedDocbookMarkup.COLSEP_ATTRIBUTE, sep );
 
             writeStartTag( SimplifiedDocbookMarkup.INFORMALTABLE_TAG, att );
 
             out.write( tableRows  );
 
             writeEndTag( SimplifiedDocbookMarkup.INFORMALTABLE_TAG );
         }
 
         tableRows = null;
         tableHasGrid = false;
     }
 
     /**
      * {@inheritDoc}
      * @see SimplifiedDocbookMarkup#TGROUP_TAG
      * @see SimplifiedDocbookMarkup#COLS_ATTRIBUTE
      * @see SimplifiedDocbookMarkup#COLSPEC_TAG
      */
     public void tableRows( int[] justification, boolean grid )
     {
         tableHasGrid = grid;
 
         // Divert output to a string ---
         out.flush();
         savedOut = out;
         tableRowsWriter = new StringWriter();
         out = new PrintWriter( tableRowsWriter );
 
         MutableAttributeSet att = new SimpleAttributeSet();
         att.addAttribute( SimplifiedDocbookMarkup.COLS_ATTRIBUTE, String.valueOf( justification.length ) );
 
         writeStartTag( SimplifiedDocbookMarkup.TGROUP_TAG, att );
 
         for ( int i1 : justification )
         {
             String justif;
             switch ( i1 )
             {
                 case Sink.JUSTIFY_LEFT:
                     justif = "left";
                     break;
                 case Sink.JUSTIFY_RIGHT:
                     justif = "right";
                     break;
                 case Sink.JUSTIFY_CENTER:
                 default:
                     justif = "center";
                     break;
             }
 
             att = new SimpleAttributeSet();
             att.addAttribute( "align", justif );
 
             writeSimpleTag( SimplifiedDocbookMarkup.COLSPEC_TAG, att );
         }
 
         writeStartTag( SimplifiedDocbookMarkup.TBODY_TAG );
     }
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#TGROUP_TAG
      * @see SimplifiedDocbookMarkup#TBODY_TAG
      */
     public void tableRows_()
     {
         writeEndTag( SimplifiedDocbookMarkup.TBODY_TAG );
         writeEndTag( SimplifiedDocbookMarkup.TGROUP_TAG );
 
         // Remember diverted output and restore original destination ---
         out.flush();
         if ( tableRowsWriter == null )
         {
             throw new IllegalArgumentException( "tableRows( int[] justification, boolean grid )"
                                                 + " was not called before." );
         }
 
         tableRows = tableRowsWriter.toString();
         tableRowsWriter = null;
         out = savedOut;
     }
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#ROW_TAG
      */
     public void tableRow()
     {
         writeStartTag( SimplifiedDocbookMarkup.ROW_TAG );
     }
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#ROW_TAG
      */
     public void tableRow_()
     {
         writeEndTag( SimplifiedDocbookMarkup.ROW_TAG );
     }
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#ENTRY_TAG
      */
     public void tableCell()
     {
         writeStartTag( SimplifiedDocbookMarkup.ENTRY_TAG );
     }
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#ENTRY_TAG
      */
     public void tableCell_()
     {
         writeEndTag( SimplifiedDocbookMarkup.ENTRY_TAG );
     }
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#ENTRY_TAG
      */
     public void tableHeaderCell()
     {
         writeStartTag( SimplifiedDocbookMarkup.ENTRY_TAG );
     }
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#ENTRY_TAG
      */
     public void tableHeaderCell_()
     {
         writeEndTag( SimplifiedDocbookMarkup.ENTRY_TAG );
     }
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#TABLE_TAG
      * @see SimplifiedDocbookMarkup#FRAME_ATTRIBUTE
      * @see SimplifiedDocbookMarkup#ROWSEP_ATTRIBUTE
      * @see SimplifiedDocbookMarkup#COLSEP_ATTRIBUTE
      * @see SimplifiedDocbookMarkup#TITLE_TAG
      */
     public void tableCaption()
     {
         tableHasCaption = true;
 
         String frame;
         int sep;
         if ( tableHasGrid )
         {
             frame = "all";
             sep = 1;
         }
         else
         {
             frame = "none";
             sep = 0;
         }
 
         MutableAttributeSet att = new SimpleAttributeSet();
         att.addAttribute( SimplifiedDocbookMarkup.FRAME_ATTRIBUTE, frame );
         att.addAttribute( SimplifiedDocbookMarkup.ROWSEP_ATTRIBUTE, String.valueOf( sep ) );
         att.addAttribute( SimplifiedDocbookMarkup.COLSEP_ATTRIBUTE, String.valueOf( sep ) );
 
         writeStartTag( TABLE_TAG, att );
 
         writeStartTag( SimplifiedDocbookMarkup.TITLE_TAG );
     }
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#TITLE_TAG
      */
     public void tableCaption_()
     {
         writeEndTag( SimplifiedDocbookMarkup.TITLE_TAG );
     }
 
     /**
      * {@inheritDoc}
      * @see SimplifiedDocbookMarkup#ANCHOR_TAG
      */
     public void anchor( String name )
     {
         if ( name == null )
         {
             throw new NullPointerException( "Anchor name cannot be null!" );
         }
 
         if ( authorDateFlag )
         {
             return;
         }
 
         String id = name;
 
         if ( !DoxiaUtils.isValidId( id ) )
         {
             id = DoxiaUtils.encodeId( name, true );
 
             String msg = "Modified invalid anchor name: '" + name + "' to '" + id + "'";
             logMessage( "modifiedLink", msg );
         }
 
         MutableAttributeSet att = new SimpleAttributeSet();
         att.addAttribute( ID_ATTRIBUTE, id );
 
         writeSimpleTag( SimplifiedDocbookMarkup.ANCHOR_TAG, att );
     }
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#ANCHOR_TAG
      */
     public void anchor_()
     {
         comment( " anchor_end " );
     }
 
     /**
      * {@inheritDoc}
      * @see SimplifiedDocbookMarkup#ULINK_TAG
      * @see SimplifiedDocbookMarkup#URL_ATTRIBUTE
      * @see SimplifiedDocbookMarkup#LINK_TAG
      * @see SimplifiedDocbookMarkup#LINKEND_ATTRIBUTE
      */
     public void link( String name )
     {
         if ( name == null )
         {
             throw new NullPointerException( "Link name cannot be null!" );
         }
 
         if ( DoxiaUtils.isInternalLink( name ) )
         {
             String linkend = name.substring( 1 );
             MutableAttributeSet att = new SimpleAttributeSet();
             att.addAttribute( SimplifiedDocbookMarkup.LINKEND_ATTRIBUTE, escapeHTML( linkend ) );
 
             writeStartTag( SimplifiedDocbookMarkup.LINK_TAG, att );
         }
         else
         {
             externalLinkFlag = true;
             MutableAttributeSet att = new SimpleAttributeSet();
             att.addAttribute( SimplifiedDocbookMarkup.URL_ATTRIBUTE, escapeHTML( name, true ) );
 
             writeStartTag( SimplifiedDocbookMarkup.ULINK_TAG, att );
         }
     }
 
     /**
      * {@inheritDoc}
      *
      * @see SimplifiedDocbookMarkup#ULINK_TAG
      * @see SimplifiedDocbookMarkup#LINK_TAG
      */
     public void link_()
     {
         if ( externalLinkFlag )
         {
             writeEndTag( SimplifiedDocbookMarkup.ULINK_TAG );
             externalLinkFlag = false;
         }
         else
         {
             writeEndTag( SimplifiedDocbookMarkup.LINK_TAG );
         }
     }
 
     /**
      * {@inheritDoc}
      */
     public void inline()
     {
         inline( null );
     }
 
     /** {@inheritDoc} */
     public void inline( SinkEventAttributes attributes )
     {
         List<String> tags = new ArrayList<>();
 
         if ( attributes != null )
         {
 
             if ( attributes.containsAttribute( SinkEventAttributes.SEMANTICS, "italic" ) )
             {
                 markup( italicBeginTag );
                 tags.add( 0, italicEndTag );
             }
 
             if ( attributes.containsAttribute( SinkEventAttributes.SEMANTICS, "bold" ) )
             {
                 write( boldBeginTag );
                 tags.add( 0, boldEndTag );
             }
 
             if ( attributes.containsAttribute( SinkEventAttributes.SEMANTICS, "code" ) )
             {
                 if ( !authorDateFlag )
                 {
                     write( monospacedBeginTag );
                     tags.add( 0, monospacedEndTag );
                 }
             }
 
         }
 
         inlineStack.push( tags );
     }
 
     /**
      * {@inheritDoc}
      */
     public void inline_()
     {
         for ( String tag: inlineStack.pop() )
         {
             markup( tag );
         }
     }
 
     /**
      * {@inheritDoc}
      */
     public void italic()
     {
         inline( SinkEventAttributeSet.Semantics.ITALIC );
     }
 
     /**
      * {@inheritDoc}
      */
     public void italic_()
     {
         inline_();
     }
 
     /**
      * {@inheritDoc}
      */
     public void bold()
     {
         inline( SinkEventAttributeSet.Semantics.BOLD );
     }
 
     /**
      * {@inheritDoc}
      */
     public void bold_()
     {
         inline_();
     }
 
     /**
      * {@inheritDoc}
      */
     public void monospaced()
     {
         inline( SinkEventAttributeSet.Semantics.CODE );
     }
 
     /**
      * {@inheritDoc}
      */
     public void monospaced_()
     {
         inline_();
     }
 
     /**
      * {@inheritDoc}
      */
     public void lineBreak()
     {
         markup( lineBreakElement );
     }
 
     /**
      * {@inheritDoc}
      */
     public void nonBreakingSpace()
     {
         markup( "&#x00A0;" );
         //markup( "&nbsp;" );
     }
 
     /** {@inheritDoc} */
     public void text( String text )
     {
         if ( verbatimFlag )
         {
             verbatimContent( text );
         }
         else
         {
             content( text );
         }
     }
 
     /** {@inheritDoc} */
     public void comment( String comment )
     {
         if ( comment != null )
         {
             String originalComment = comment;
 
             // http://www.w3.org/TR/2000/REC-xml-20001006#sec-comments
             while ( comment.contains( "--" ) )
             {
                 comment = comment.replace( "--", "- -" );
             }
 
             if ( comment.endsWith( "-" ) )
             {
                 comment += " ";
             }
 
             if ( !originalComment.equals( comment ) )
             {
                 String msg = "Modified invalid comment: '" + originalComment + "' to '" + comment + "'";
                 logMessage( "modifiedComment", msg );
             }
 
             StringBuilder buffer = new StringBuilder( comment.length() + 7 );
 
             buffer.append( LESS_THAN ).append( BANG ).append( MINUS ).append( MINUS );
             buffer.append( comment );
             buffer.append( MINUS ).append( MINUS ).append( GREATER_THAN );
 
             markup( buffer.toString() );
         }
     }
 
     /**
      * {@inheritDoc}
      *
      * Unknown events just log a warning message but are ignored otherwise.
      * @see org.apache.maven.doxia.sink.Sink#unknown(String,Object[],SinkEventAttributes)
      */
     public void unknown( String name, Object[] requiredParams, SinkEventAttributes attributes )
     {
         String msg = "Unknown Sink event: '" + name + "', ignoring!";
         logMessage( "unknownEvent", msg );
     }
 
     // -----------------------------------------------------------------------
 
     /**
      * Write text to output, preserving white space.
      *
      * @param text The text to write.
      */
     protected void markup( String text )
     {
         if ( !skip )
         {
             out.write( text );
         }
     }
 
     /**
      * Write SGML escaped text to output, not preserving white space.
      *
      * @param text The text to write.
      */
     protected void content( String text )
     {
         if ( !skip )
         {
             out.write( escapeHTML( text, true ) );
         }
     }
 
     /**
      * Write SGML escaped text to output, preserving white space.
      *
      * @param text The text to write.
      */
     protected void verbatimContent( String text )
     {
         if ( !skip )
         {
             out.write( escapeHTML( text, true ) );
         }
     }
 
     // -----------------------------------------------------------------------
 
     /**
      * {@inheritDoc}
      */
     public void flush()
     {
         out.flush();
     }
 
     /**
      * {@inheritDoc}
      */
     public void close()
     {
         out.close();
 
         if ( getLog().isWarnEnabled() && this.warnMessages != null )
         {
             for ( Map.Entry<String, Set<String>> entry : this.warnMessages.entrySet() )
             {
                 for ( String msg : entry.getValue() )
                 {
                     getLog().warn( msg );
                 }
             }
 
             this.warnMessages = null;
         }
     }
 
     /** {@inheritDoc} */
     protected void write( String text )
     {
         markup( unifyEOLs( text ) );
     }
 
     /**
      * <p>Setter for the field <code>skip</code>.</p>
      *
      * @param skip the skip to set.
      * @since 1.1
      */
     public void setSkip( boolean skip )
     {
         this.skip = skip;
     }
 
     /**
      * If debug mode is enabled, log the <code>msg</code> as is, otherwise add unique msg in <code>warnMessages</code>.
      *
      * @param key not null
      * @param msg not null
      * @see #close()
      * @since 1.1.1
      */
     private void logMessage( String key, String msg )
     {
         msg = "[Docbook Sink] " + msg;
         if ( getLog().isDebugEnabled() )
         {
             getLog().debug( msg );
 
             return;
         }
 
         if ( warnMessages == null )
         {
             warnMessages = new HashMap<>();
         }
 
         Set<String> set = warnMessages.get( key );
         if ( set == null )
         {
             set = new TreeSet<>();
         }
         set.add( msg );
         warnMessages.put( key, set );
     }
 }