code: protected static Set<String> resolveIncludeExcludeString( String input, File basedir )
          throws MojoExecutionException
      {
          Set<String> inclExlSet = new LinkedHashSet<String>();
          try
          {
              if ( null == input || input.trim().equals( "" ) )
              {
                  return inclExlSet;
              }
              String[] elements = input.split( "," );
              if ( null != elements )
              {
  
                  for ( int i = 0; i < elements.length; i++ )
                  {
                      String element = elements[i];
                      if ( element.endsWith( ".java" ) || element.endsWith( ".aj" ) )
                      {
                          inclExlSet.addAll( FileUtils.getFileNames( basedir, element, "", true ) );
                      }
                      else
                      {
                          File lookupBaseDir = new File( basedir, element );
                          if ( FileUtils.fileExists( lookupBaseDir.getAbsolutePath() ) )
                          {
                              inclExlSet.addAll( FileUtils.getFileNames( lookupBaseDir, DEFAULT_INCLUDES, "",
                                                                     true ) );
                          }
                      }
                  }
              }
          }
          catch ( IOException e )
          {
              throw new MojoExecutionException( "Could not resolve java or aspect sources to compile", e );
          }
          return inclExlSet;
      }
docs: Helper method to find all .java or .aj files specified by the
  includeString. The includeString is a comma separated list over files, or
  directories relative to the specified basedir. Examples of correct
  listings
  
  <pre>
  src/main/java/
  src/main/java
  src/main/java/com/project/AClass.java
  src/main/java/com/project/AnAspect.aj
  src/main/java/com/project/AnAspect.java
  </pre>
  
  @param input
  @param basedir the baseDirectory
  @return a list over all files inn the include string
  @throws IOException