// takes ~70 ms to set up, do it only once if possible
sclass ClassNameResolver {
  settable File byteCodePath = byteCodePathForClass(getClass());
  LS importedPackages = itemPlusList("java.lang",
    endingWith_dropSuffix(standardImports(), ".*"));
  
  simplyCached Set<S> allFullyQualifiedClassNames() {
    new Set<S> set;
    assertNotNull(byteCodePath);
    set.addAll(classNamesInJarOrDir(byteCodePath));
    printVars ClassNameResolver(+byteCodePath, classesFound := l(set));
    set.addAll(classNamesInLoadedJigsawModules());
    ret set;
  }
  
  selfType init() { allFullyQualifiedClassNames(); this; }

  S findClass(S name) {
    for (S pkg : importedPackages) {
      S fullName = pkg + "." + name;
      if (allFullyQualifiedClassNames().contains(fullName))
        ret fullName;
    }
    null;
  }
  
  void printMe {
    printVars("ClassNameResolver", +byteCodePath);
    print(+importedPackages);
  }
}