anchor.diff:  
   # filters
   assert enableExtraPlugins || enableDitaaFilter || enableMscgenFilter || enableDiagFilter || enableQrcodeFilter || enableAafigureFilter -> unzip != null;
  -assert enableExtraPlugins || enableDitaaFilter -> jre != null;
  +assert (enableExtraPlugins && enableJava) || enableDitaaFilter -> jre != null;
   assert enableExtraPlugins || enableMscgenFilter -> mscgen != null;
   assert enableExtraPlugins || enableDiagFilter -> blockdiag != null && seqdiag != null && actdiag != null && nwdiag != null;
   assert enableExtraPlugins || enableMatplotlibFilter -> matplotlib != null && numpy != null;
  
positive.code:         -e "s|^ASCIIDOC =.*|ASCIIDOC = '$out/bin/asciidoc'|" \
          -e "s|^XSLTPROC =.*|XSLTPROC = '${libxslt.bin}/bin/xsltproc'|" \
          -e "s|^DBLATEX =.*|DBLATEX = '${dblatexFull}/bin/dblatex'|" \
          -e "s|^FOP =.*|FOP = '${fop}/bin/fop'|" \
          -e "s|^W3M =.*|W3M = '${w3m}/bin/w3m'|" \
          -e "s|^LYNX =.*|LYNX = '${lynx}/bin/lynx'|" \
          -e "s|^XMLLINT =.*|XMLLINT = '${libxml2.bin}/bin/xmllint'|" \
  
negative.code: 
  let
  
    _enableDitaaFilter = (enableExtraPlugins && enableJava) || enableDitaaFilter;
    _enableMscgenFilter = enableExtraPlugins || enableMscgenFilter;
    _enableDiagFilter = enableExtraPlugins || enableDiagFilter;
    _enableQrcodeFilter = enableExtraPlugins || enableQrcodeFilter;
  