public HadoopStepConfig withMainClass(String mainClass) {
        setMainClass(mainClass);
        return this;
    }
<p>
The name of the main class in the specified Java file. If not specified, the JAR file should specify a main class
in its manifest file.
</p>

@param mainClass
       The name of the main class in the specified Java file. If not specified, the JAR file should specify a
       main class in its manifest file.
@return Returns a reference to this object so that method calls can be chained together.
aws-java-sdk-emr/src/main/java/com/amazonaws/services/elasticmapreduce/model/HadoopStepConfig.java