download_url: account for elasticsearch 6

Author: haarg

lib/MetaCPAN/Query/Release.pm

@@ -1025,19 +1025,25 @@ sub find_download_url {
         ? { bool => { must => \@filters } }
         : $filters[0];
 
-    my $version_sort = $module_filter
+    my $version_sort
+        = $module_filter
         ? {
         'module.version_numified' => {
-            mode          => 'max',
-            order         => 'desc',
-            nested_path   => 'module',
-            nested_filter => $entity_filter,
-
-            # TODO: ES6 - replace prior 2 lines with:
-            #nested => {
-            #    path => 'module',
-            #    filter => $entity_filter,
-            #},
+            mode  => 'max',
+            order => 'desc',
+            (
+                $self->es->api_version ge '6_0'
+                ? (
+                    nested => {
+                        path   => 'module',
+                        filter => $entity_filter,
+                    },
+                    )
+                : (
+                    nested_path   => 'module',
+                    nested_filter => $entity_filter,
+                )
+            ),
         }
         }
         : { version_numified => { order => 'desc' } };