Bug 78317 Compare plug-in gets loaded by LocalHistoryActionGroup
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/compare/JavaAddElementFromHistory.java
if (element instanceof IStreamContentAccessor) {
			String content= JavaCompareUtilities.readString((IStreamContentAccessor)element);
			if (content != null) {
				content= trimTextBlock(content, delimiter);
				if (content != null) {
				    int type= getPlaceHolderType(element);
				    if (type != -1)
				        return rewriter.createStringPlaceholder(content, type);
				}
			}
		}
		return null;
	}
	
	/**
	 * Finds the corresponding ASTNode for the given container and returns 
	 * its list of children. This list can be used to add a new child nodes to the container.
	 * @param container the container for which to return the children list
	 * @param root the AST
	 * @return list of children or null
	 * @throws JavaModelException
	 */
	private List getContainerList(IParent container, CompilationUnit root) throws JavaModelException {
		
		if (container instanceof ICompilationUnit)
			return root.types();
			
		if (container instanceof IType) {
			ISourceRange sourceRange= ((IType)container).getNameRange();
			ASTNode n= NodeFinder.perform(root, sourceRange);