right semantics for backwards compatibility

Author: twogee

src/java/org/apache/ivy/plugins/resolver/AbstractResolver.java

@@ -20,7 +20,6 @@
 import java.io.File;
 import java.io.IOException;
 import java.util.Arrays;
-import java.util.Collections;
 import java.util.Date;
 import java.util.HashSet;
 import java.util.Map;
@@ -181,15 +180,22 @@ public String[] listTokenValues(String token, Map<String, String> otherTokenValu
         return new String[0];
     }
 
+    // new API: provide the default implementation for third party implementations that lack it
+    @SuppressWarnings("deprecation")
     public Set<Map<String, String>> listTokenValues(Set<String> tokens, Map<String, Object> criteria) {
-        return Collections.emptySet();
+        Set<Map<String, String>> tokenValueSet = new HashSet<>();
+         for (Map<String, String> tokenValue :
+                 listTokenValues(tokens.toArray(new String[tokens.size()]), criteria)) {
+             tokenValueSet.add(tokenValue);
+         }
+         return tokenValueSet;
     }
 
+    // old API
     @SuppressWarnings("unchecked")
     @Deprecated
     public Map<String, String>[] listTokenValues(String[] tokens, Map<String, Object> criteria) {
-        Set<Map<String, String>> listTokenValues = listTokenValues(new HashSet<>(Arrays.asList(tokens)), criteria);
-        return listTokenValues.toArray(new Map[listTokenValues.size()]);
+        return new Map[0];
     }
 
     public OrganisationEntry[] listOrganisations() {

src/java/org/apache/ivy/plugins/resolver/ChainResolver.java

@@ -181,12 +181,21 @@ public ResolvedResource findIvyFileRef(DependencyDescriptor dd, ResolveData data
     }
 
     @Override
+    @SuppressWarnings("deprecation")
     public Set<Map<String, String>> listTokenValues(Set<String> tokens, Map<String, Object> criteria) {
         Set<Map<String, String>> result = new HashSet<>();
         for (DependencyResolver resolver : chain) {
-            result.addAll(resolver.listTokenValues(tokens, new HashMap<>(criteria)));
+            if (resolver instanceof AbstractResolver) {
+                // new API
+                result.addAll(resolver.listTokenValues(tokens, new HashMap<>(criteria)));
+            } else {
+                // old API
+                for (Map<String, String> tokenValue :
+                        resolver.listTokenValues(tokens.toArray(new String[tokens.size()]), criteria)) {
+                    result.add(tokenValue);
+                }
+            }
         }
-
         return result;
     }