public Builder putRequestParameter(String input, String output) {
            requestParameters.put(input, output);
            return this;
        }
Adds a request parameters.

@param input Input request expression.
@param output Output request expression.
@return Returns the builder.
@see IntegrationTrait#getRequestParameters()
smithy-aws-apigateway-traits/src/main/java/software/amazon/smithy/aws/apigateway/traits/MockIntegrationTrait.java