Fix #16976.

Author: dkocher

googledrive/src/main/java/ch/cyberduck/core/googledrive/DriveAttributesFinderFeature.java

@@ -128,6 +128,9 @@ public PathAttributes toAttributes(final File f) {
                         .getBytes(Charset.defaultCharset()).length);
             }
         }
+        if(null != f.getProperties()) {
+            attributes.setMetadata(f.getProperties());
+        }
         return attributes;
     }
 }

googledrive/src/main/java/ch/cyberduck/core/googledrive/DriveMetadataFeature.java

@@ -23,10 +23,13 @@
 
 import java.io.IOException;
 import java.util.Collections;
+import java.util.HashMap;
 import java.util.Map;
 
 import com.google.api.services.drive.model.File;
 
+import static com.google.api.client.util.Data.NULL_STRING;
+
 public class DriveMetadataFeature implements Metadata {
 
     private final DriveSession session;
@@ -63,10 +66,18 @@ public void setMetadata(final Path file, final TransferStatus status) throws Bac
         try {
             final String fileid = this.fileid.getFileId(file);
             final File body = new File();
-            body.setProperties(status.getMetadata());
-            final File properties = session.getClient().files().update(fileid, body).setFields("properties").
-                    setSupportsAllDrives(HostPreferencesFactory.get(session.getHost()).getBoolean("googledrive.teamdrive.enable")).execute();
-            status.setResponse(new DriveAttributesFinderFeature(session, this.fileid).toAttributes(properties));
+            final Map<String, String> properties = new HashMap<>(status.getMetadata());
+            for(String key : file.attributes().getMetadata().keySet()) {
+                if(!properties.containsKey(key)) {
+                    // Entries with null values are cleared in update and copy requests
+                    properties.put(key, NULL_STRING);
+                }
+            }
+            body.setProperties(properties);
+            status.setResponse(new DriveAttributesFinderFeature(session, this.fileid).toAttributes(
+                    session.getClient().files().update(fileid, body).setFields("properties").
+                            setSupportsAllDrives(HostPreferencesFactory.get(session.getHost()).getBoolean("googledrive.teamdrive.enable")).execute()
+            ));
         }
         catch(IOException e) {
             throw new DriveExceptionMappingService(fileid).map("Failure to write attributes of {0}", e, file);

googledrive/src/test/java/ch/cyberduck/core/googledrive/DriveMetadataFeatureTest.java

@@ -29,6 +29,7 @@
 
 import java.util.Collections;
 import java.util.EnumSet;
+import java.util.Map;
 import java.util.UUID;
 
 import static ch.cyberduck.core.googledrive.DriveHomeFinderService.MYDRIVE_FOLDER;
@@ -39,14 +40,20 @@ public class DriveMetadataFeatureTest extends AbstractDriveTest {
 
     @Test
     public void setMetadata() throws Exception {
-        final Path home = DriveHomeFinderService.MYDRIVE_FOLDER;
-        final Path test = new Path(home, UUID.randomUUID().toString(), EnumSet.of(Path.Type.file));
+        final Path test = new Path(DriveHomeFinderService.MYDRIVE_FOLDER, UUID.randomUUID().toString(), EnumSet.of(Path.Type.file));
         final DriveFileIdProvider fileid = new DriveFileIdProvider(session);
-        new DriveTouchFeature(session, fileid).touch(test, new TransferStatus());
-        assertEquals(Collections.emptyMap(), new DriveMetadataFeature(session, fileid).getMetadata(test));
-        new DriveMetadataFeature(session, fileid).setMetadata(test, Collections.singletonMap("test", "t"));
-        assertEquals(Collections.singletonMap("test", "t"), new DriveMetadataFeature(session, fileid).getMetadata(test));
-        new DriveDeleteFeature(session, fileid).delete(Collections.<Path>singletonList(test), new DisabledLoginCallback(), new Delete.DisabledCallback());
+        final TransferStatus status = new TransferStatus();
+        new DriveTouchFeature(session, fileid).touch(test, status);
+        final DriveMetadataFeature feature = new DriveMetadataFeature(session, fileid);
+        assertEquals(Collections.emptyMap(), feature.getMetadata(test));
+        feature.setMetadata(test, Collections.singletonMap("test", "t"));
+        final Map<String, String> metadata = feature.getMetadata(test);
+        assertEquals(Collections.singletonMap("test", "t"), metadata);
+        test.attributes().setMetadata(metadata);
+        feature.setMetadata(test, status.setMetadata(Collections.emptyMap()));
+        assertFalse(status.getResponse().getMetadata().containsKey("test"));
+        assertFalse(feature.getMetadata(test).containsKey("test"));
+        new DriveDeleteFeature(session, fileid).delete(Collections.singletonList(test), new DisabledLoginCallback(), new Delete.DisabledCallback());
     }
 
     @Test