code: public ServicePoolBuilder<S> withPartitionContextAnnotationsFrom(Class<? extends S> annotatedServiceClass) {
          checkNotNull(annotatedServiceClass);
          _partitionContextSupplier = new AnnotationPartitionContextSupplier(_serviceType, annotatedServiceClass);
          return this;
      }
docs: Uses {@link PartitionKey} annotations from the specified class to generate partition context in the built proxy.
  <p>
  NOTE: This is only useful if building a proxy with {@link #buildProxy(com.bazaarvoice.ostrich.RetryPolicy)}.  If
  partition context is necessary with a normal service pool, then can be provided directly by calling
  {@link com.bazaarvoice.ostrich.ServicePool#execute(com.bazaarvoice.ostrich.PartitionContext,
  com.bazaarvoice.ostrich.RetryPolicy, com.bazaarvoice.ostrich.ServiceCallback)}.
  
  @param annotatedServiceClass A service class with {@link PartitionKey} annotations.
  @return this