code: @CheckForNull
      private DetailAST getExprAst(@Nonnull final DetailAST pAst)
      {
          DetailAST result = null;
          for (DetailAST a = pAst.getFirstChild(); a != null; a = a.getNextSibling()) {
              if (a.getType() != TokenTypes.LPAREN && a.getType() != TokenTypes.RPAREN) {
                  result = a;
                  break;
              }
          }
          return result;
      }
docs: Find the "meaningful" child of an EXPR AST. This is usually the only child present, but it may be surrounded by
  parentheses.
  
  @param pAst an EXPR AST
  @return the meaningful child of the EXPR, or <code>null</code> if such could not be determined