public Builder shared(@Nullable Boolean shared) {
      if (shared != null) return shared((boolean) shared);
      flags &= ~(FLAG_SHARED_SET | FLAG_SHARED);
      return this;
    }
public Builder shared ( @ Nullable Boolean shared ) { if ( shared != null ) return shared ( ( boolean ) shared ) ; flags &= ~ ( FLAG_SHARED_SET | FLAG_SHARED ) ; return this ; }
@see Span#shared