code: private void enterMember(ClassSymbol c, Symbol sym) {
          // Synthetic members are not entered -- reason lost to history (optimization?).
          // Lambda methods must be entered because they may have inner classes (which reference them)
          if ((sym.flags_field & (SYNTHETIC|BRIDGE)) != SYNTHETIC || sym.name.startsWith(names.lambda))
              c.members_field.enter(sym);
      }
docs: Add member to class unless it is synthetic.