// Input class will encapsulate the following three things: name, args, splits
public class Input {
  private final String datasetName;
  private final Map<String, String> arguments;
  private final List<Split> splits;

  // ...

} 


// The new APIs on MapReduceContext will be:
void addInput(Input input);
void addInput(StreamBatchReadable stream);
void addInput(String inputName, InputFormatProvider inputFormatProvider);

void addInput(Input input, MapperClass<?> mappermapperCls);
void addInput(StreamBatchReadable stream, MapperClass<?> mappermapperCls);
void addInput(String inputName, InputFormatProvider inputFormatProvider, MapperClass<?> mappermapperCls);