streamObserver
Creates a StreamObserver using a DSL-style builder.
Every callback is optional, and each one may be registered at most once: a second StreamObserverHelper.onNext, StreamObserverHelper.onError or StreamObserverHelper.onCompleted in the same block throws IllegalStateException.
Return
a StreamObserver that delegates to the registered callbacks
Parameters
init
a configuration block for registering StreamObserverHelper.onNext, StreamObserverHelper.onError, and StreamObserverHelper.onCompleted callbacks
Type Parameters
T
the response element type