ParcelablePlease-intellij-plugin/src/com/hannesdorfmann/parcelableplease/plugin/CodeGenerator.java
private void addAnnotation(PsiElementFactory elementFactory, JavaCodeStyleManager styleManager) {

    boolean annotated = AnnotationUtil.isAnnotated(psiClass, ANNOTATION_PACKAGE+"."+ANNOTATION_NAME, false);

    if (!annotated) {
      styleManager.shortenClassReferences(psiClass.getModifierList().addAnnotation(
          ANNOTATION_NAME));
    }
  }
private void addAnnotation(PsiElementFactory elementFactory, JavaCodeStyleManager styleManager) {

    boolean annotated = AnnotationUtil.isAnnotated(psiClass, ANNOTATION_PACKAGE+"."+ANNOTATION_NAME, false);

    if (!annotated) {
      styleManager.shortenClassReferences(psiClass.getModifierList().addAnnotation(
          ANNOTATION_NAME));
    }
  }
Add the @Parcelable annotation if not already annotated