code: public CredentialInner update(String resourceGroupName, String automationAccountName, String credentialName, CredentialUpdateParameters parameters) {
          return updateWithServiceResponseAsync(resourceGroupName, automationAccountName, credentialName, parameters).toBlocking().single().body();
      }
docs: Update a credential.
  
  @param resourceGroupName Name of an Azure Resource group.
  @param automationAccountName The name of the automation account.
  @param credentialName The parameters supplied to the Update credential operation.
  @param parameters The parameters supplied to the Update credential operation.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @throws ErrorResponseException thrown if the request is rejected by server
  @throws RuntimeException all other wrapped checked exceptions if the request fails to be sent
  @return the CredentialInner object if successful.