code: public PrimaryKey addComponents(KeyAttribute ... components) {
          if (components != null) {
              for (KeyAttribute ka: components) {
                  InternalUtils.rejectNullInput(ka);
                  this.components.put(ka.getName(), ka);
              }
          }
          return this;
      }
docs: Add one or multiple key components to this primary key.
  
  Note adding a key component with the same name as that of an existing
  one would overwrite and become a single key component instead of two.