code: @Override
      public boolean isOptional()
      {
          boolean isNullable = true;
          if (!isId())
          {
              Column anno = member.getAnnotation(Column.class);
              if (anno != null)
              {
                  isNullable = anno.nullable();
              }
          }
          else
          {
              isNullable = false;
          }
          return isNullable;
      }
docs: /*
  (non-Javadoc)
  
  @see javax.persistence.metamodel.SingularAttribute#isOptional()