code: public PackageDocImpl lookupPackage(String name) {
          //### Jing alleges that class check is needed
          //### to avoid a compiler bug.  Most likely
          //### instead a dummy created for error recovery.
          //### Should investigate this.
          Name nameImpl = names.fromString(name);
          ModuleSymbol mod = syms.inferModule(nameImpl);
          PackageSymbol p = mod != null ? syms.getPackage(mod, nameImpl) : null;
          ClassSymbol c = getClassSymbol(name);
          if (p != null && c == null) {
              return getPackageDoc(p);
          } else {
              return null;
          }
      }
docs: Look up PackageDoc by qualified name.