In ensureValidHierarchy(), don't allow one paragraph node to be a child of another
In ensureValidHierarchy(), don't allow one paragraph node to be a child of another

corinthia/corinthia-editor,corinthia/corinthia-editorlib,corinthia/corinthia-editorlib,corinthia/corinthia-editor,corinthia/corinthia-editorlib,corinthia/corinthia-editorlib,corinthia/corinthia-editor,corinthia/corinthia-editor,corinthia/corinthia-editorlib,corinthia/corinthia-editor