EditorTextField not supporting any syntax highlights

Hi,

I have used the below code to create a EditorTextField but it is not supporting any kind of syntax checks, please let me know, what is wrong?

private EditorTextField createEditorTextField(String content){
       EditorFactory editorFactory = EditorFactory.getInstance();
       Document document = editorFactory.createDocument(content);
       EditorTextField field = new EditorTextField(document, null, JsonFileType.INSTANCE);
       field.setOneLineMode(false);
       field.setCaretPosition(0);
       return field;
   }