@Nullable
  public static GrExpression findExpression(PsiFile file, int startOffset, int endOffset) {
    GrExpression selectedExpr = PsiImplUtil.findElementInRange(file, startOffset, endOffset, GrExpression.class);
    return findExpression(selectedExpr);
  }
@Nullable
  public static GrExpression findExpression(PsiFile file, int startOffset, int endOffset)