code: public String getExpressionString() {
          StringBuffer buf = new StringBuffer();
          buf.append("(");
          buf.append(mExpression.getExpressionString());
          for (int i = 0; i < mOperators.size(); i++) {
              BinaryOperator operator = (BinaryOperator) mOperators.get(i);
              Expression expression = (Expression) mExpressions.get(i);
              buf.append(" ");
              buf.append(operator.getOperatorSymbol());
              buf.append(" ");
              buf.append(expression.getExpressionString());
          }
          buf.append(")");
  
          return buf.toString();
      }
docs: Returns the expression in the expression language syntax