Update DjlDnnModel.java

Support multiple outputs.
Aims to address #15

src/main/java/qupath/ext/djl/DjlDnnModel.java

@@ -35,6 +35,7 @@
 import java.net.URI;
 import java.util.ArrayList;
 import java.util.Collection;
+import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Objects;
@@ -127,7 +128,18 @@ public Map<String, Mat> predict(Map<String, Mat> blobs) {
 		synchronized (predictor) {
 			try {
 				var result = predictor.predict(blobs.values().stream().toArray(Mat[]::new));
-				return Map.of(DnnModel.DEFAULT_OUTPUT_NAME, result[0]);
+				if (result.length == 1)
+					return Map.of(DnnModel.DEFAULT_OUTPUT_NAME, result[0]);
+				else if (result.length == 0)
+					return Map.of();
+				else {
+					// Try to handle multiple outputs, naming them sequentially
+					Map<String, Mat> output = new LinkedHashMap<>();
+					for (int i = 0; i < result.length; i++) {
+						output.put(DEFAULT_OUTPUT_NAME + i, result[i]);
+					}
+					return output;
+				}
 			} catch (TranslateException e) {
 				throw new RuntimeException(e);
 			}
@@ -195,7 +207,7 @@ private class ModelMatTranslator implements NoBatchifyTranslator<Mat[], Mat[]> {
 		@Override
 		public Mat[] processOutput(TranslatorContext ctx, NDList list) throws Exception {
 			String layout;
-			if ((ndLayout == null || ndLayout.length() != list.singletonOrThrow().getShape().dimension()) && !list.isEmpty())
+			if ((ndLayout == null || ndLayout.length() != list.get(0).getShape().dimension()) && !list.isEmpty())
 				layout = estimateOutputLayout(list.get(0));
 			else
 				layout = ndLayout;