public static @Nullable PsiElement getPreviousElement(final PsiElement element, boolean skipReference){
    PsiElement prev = element;
    if(element != null){
      if(skipReference){
        prev = FilterPositionUtil.searchNonSpaceNonCommentBack(element);
        while(prev != null && prev.getParent() instanceof PsiJavaCodeReferenceElement){
          prev = FilterPositionUtil.searchNonSpaceNonCommentBack(prev.getParent());
        }
      }
      else{
        prev = FilterPositionUtil.searchNonSpaceNonCommentBack(prev);
      }
    }
    return prev;
  }
public static @Nullable PsiElement getPreviousElement(final PsiElement element, boolean skipReference)