Method sinkInit initializes this instance as a sink.
This method is executed client side as a means to provide necessary configuration parameters used by the underlying platform.
It is not intended to initialize resources that would be necessary during the execution of this class, like a "formatter" or "parser".
See {@link #sinkPrepare(cascading.flow.FlowProcess,SinkCall)} if resources much be initializedbefore use. And {@link #sinkCleanup(cascading.flow.FlowProcess,SinkCall)} if resources must bedestroyed after use.
@param flowProcess of type FlowProcess
@param tap of type Tap
@param conf of type Config