code: public Observable<ManagedDatabaseInner> beginUpdateAsync(String resourceGroupName, String managedInstanceName, String databaseName, ManagedDatabaseUpdate parameters) {
          return beginUpdateWithServiceResponseAsync(resourceGroupName, managedInstanceName, databaseName, parameters).map(new Func1<ServiceResponse<ManagedDatabaseInner>, ManagedDatabaseInner>() {
              @Override
              public ManagedDatabaseInner call(ServiceResponse<ManagedDatabaseInner> response) {
                  return response.body();
              }
          });
      }
docs: Updates an existing database.
  
  @param resourceGroupName The name of the resource group that contains the resource. You can obtain this value from the Azure Resource Manager API or the portal.
  @param managedInstanceName The name of the managed instance.
  @param databaseName The name of the database.
  @param parameters The requested database resource state.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the ManagedDatabaseInner object