code: public Observable<PolicyAssignmentInner> createAsync(String scope, String policyAssignmentName, PolicyAssignmentInner parameters) {
          return createWithServiceResponseAsync(scope, policyAssignmentName, parameters).map(new Func1<ServiceResponse<PolicyAssignmentInner>, PolicyAssignmentInner>() {
              @Override
              public PolicyAssignmentInner call(ServiceResponse<PolicyAssignmentInner> response) {
                  return response.body();
              }
          });
      }
docs: Creates a policy assignment.
  Policy assignments are inherited by child resources. For example, when you apply a policy to a resource group that policy is assigned to all resources in the group.
  
  @param scope The scope of the policy assignment.
  @param policyAssignmentName The name of the policy assignment.
  @param parameters Parameters for the policy assignment.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the PolicyAssignmentInner object