code: public Observable<PolicyDefinitionInner> getAsync(String policyDefinitionName) {
          return getWithServiceResponseAsync(policyDefinitionName).map(new Func1<ServiceResponse<PolicyDefinitionInner>, PolicyDefinitionInner>() {
              @Override
              public PolicyDefinitionInner call(ServiceResponse<PolicyDefinitionInner> response) {
                  return response.body();
              }
          });
      }
docs: Gets the policy definition.
  
  @param policyDefinitionName The name of the policy definition to get.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the PolicyDefinitionInner object