question: public static IPackageFragmentRoot addSourceContainer ( IJavaProject jproject , String containerName , IPath [ ] inclusionFilters , IPath [ ] exclusionFilters , String outputLocation ) throws CoreException { IProject project = jproject . getProject ( ) ; IContainer container = null ; if ( containerName == null || containerName . length ( ) == 0 ) { container = project ; } else { IFolder folder = project . getFolder ( containerName ) ; if ( ! folder . exists ( ) ) { CoreUtility . createFolder ( folder , false , true , null ) ; } container = folder ; } IPackageFragmentRoot root = jproject . getPackageFragmentRoot ( container ) ; IPath outputPath = null ; if ( outputLocation != null ) { IFolder folder = project . getFolder ( outputLocation ) ; if ( ! folder . exists ( ) ) { CoreUtility . createFolder ( folder , false , true , null ) ; } outputPath = folder . getFullPath ( ) ; } IClasspathEntry cpe = JavaCore . newSourceEntry ( root . getPath ( ) , inclusionFilters , exclusionFilters , outputPath ) ; addToClasspath ( jproject , cpe ) ; return root ; }
target:  Adds a source container to a IJavaProject.