Javadoc
This method is intended to be used in case a custom
org.apache.tez.runtime.api.InputInitializeris being used along with MRInput. If a custom descriptor is used, the config builder will not be
able to setup location hints, parallelism, etc, and configuring the
org.apache.tez.dag.api.Vertex on which this Input is used is the responsibility of the user.
Credential fetching can be controlled via the
#getCredentialsForSourceFilesystem method.
Whether grouping is enabled or not can be controlled via
#groupSplitsInAM method.