@Override
    protected AWSStepFunctionsAsync build(AwsAsyncClientParams params) {
        return new AWSStepFunctionsAsyncClient(params);
    }
Construct an asynchronous implementation of AWSStepFunctionsAsync using the current builder configuration.

@param params
       Current builder configuration represented as a parameter object.
@return Fully configured implementation of AWSStepFunctionsAsync.
aws-java-sdk-stepfunctions/src/main/java/com/amazonaws/services/stepfunctions/AWSStepFunctionsAsyncClientBuilder.java