In order to create alice.keytab and bob.keytab, in src/test/resources/kerberos directory, execute the following commands depending on the underlying OS:

Windows:
<java_home>/bin/ktab.exe -a alice@EXAMPLE.COM password -k alice.keytab
<java_home>/bin/ktab.exe -a bob@EXAMPLE.COM password -k bob.keytab

Unix (requires ktutil)
ktutil add_entry -password -p alice@EXAMPLE.COM -k 1 -e aes128-cts-hmac-sha1-96\npassword\n write_kt alice.keytab\n quit
ktutil add_entry -password -p bob@EXAMPLE.COM -k 1 -e aes128-cts-hmac-sha1-96\npassword\n write_kt bob.keytab\n quit