There is an open issue at https://bugs.openjdk.java.net/browse/JDK-8187981 but it doesn't seem to be getting much traction. There is an alternative to System.getProperty but it's through swing:

import java.io.FileNotFoundException;
import javax.swing.filechooser.FileSystemView;


void setup() {
  
  // Use file view to get directories
  FileSystemView view = FileSystemView.getFileSystemView();
  File homeDirectory = view.getHomeDirectory();
  
  // Try writing to home directory
  File testHomeFile = view.createFileObject(homeDirectory, "test_home.txt");
  try {
    PrintWriter writer = new PrintWriter(testHomeFile);
    writer.print("test home");
    writer.close();
  } catch (FileNotFoundException e) {
    println("File not found exception on documents.");
  }
  
  // Try writing to documents directory
  File documentsDirectory = view.getChild(homeDirectory, "Documents");
  File testDocumentsFile = view.createFileObject(documentsDirectory, "test_docs.txt");
  try {
    PrintWriter writer = new PrintWriter(testDocumentsFile);
    writer.print("test documents");
    writer.close();
  } catch (FileNotFoundException e) {
    println("File not found exception on documents.");
  }
  
}

See https://gist.github.com/sampottinger/49aef03638b150257cca919954319f01. It does work on 10.14 with a signed application.

Open to suggestions but, unfortunately, JDK 11 isn't providing an alternative as far as I can tell? @benfry - would you like me to switch out for FileSystemView or leave this ticket as is and address in a future JDK?

I think FileSystemView would be a step backwards, so we should leave it open until we have a better fix. (Want to get AWT/Swing out of there wherever possible.)

Might be something we just need to add via JNA, since it should be a single OS call.

I agree. :(