Copying request parameter to flow scope in spring webflow

Hi All,
I am using the evaluate expression in the following manner to copy the request parameter in the spring webflow to flow scope.

<evaluate expression="requestParameters.ondCityCodeMonth" result="flowScope.depMonth"></evaluate>

In the above case the the request parameter name is ondCityCodeMonth. The below works properly.

But my requirement is that the parameter name is ondCityCode[0].month. In this case the above expression is changed to

<evaluate expression="requestParameters.ondCityCode[0].month" result="flowScope.depMonth"></evaluate>
In this case the string requestParameters.ondCityCode[0].month is taken as an expression and it throws an error that the expression cannot be evaluated.

Has anyone faced such problem. Please let me know how it can be fixed.

Thanks in advance
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