code: private void processIdentifierField(Field field) {
      Identifier identifier = field.getAnnotation(Identifier.class);
      boolean autoGenerated = identifier.autoGenerated();
      IdentifierMetadata identifierMetadata = new IdentifierMetadata(field, autoGenerated);
      entityMetadata.setIdentifierMetadata(identifierMetadata);
    }
docs: Processes the identifier field and builds the identifier metadata.
  
  @param field
  the identifier field