code: public Object resolveExpression(String expressionString, Object contextRoot) {
          if ((expressionString.startsWith("${") || expressionString.startsWith("#{")) && expressionString.endsWith("}")) {
              expressionString = expressionUtil.stripExpression(expressionString);
          }
          ExpressionParser parser = new SpelExpressionParser();
          StandardEvaluationContext evaluationContext = new StandardEvaluationContext(contextRoot);
          evaluationContextConfigurer.configureEvaluationContext(evaluationContext);
          Expression expression = parser.parseExpression(expressionString);
          return expression.getValue(evaluationContext);
      }
docs: Runs the given expression against the given context object and returns the result of the evaluated expression.
  
  @param expressionString the expression to evaluate.
  @param contextRoot      the context object against which the expression is evaluated.
  @return the result of the evaluated expression.