private Class<?> expressionReturnType(String expr) {
    final ParserContext parserContext = new ParserContext();
    parserContext.setStrictTypeEnforcement(true);
    parserContext.setStrongTyping(true);
    parserContext.addInput("this", Bean1.class);
    MVEL.compileExpression(expr, parserContext);
    return MVEL.analyze(expr, parserContext);
  }