[FIXED JENKINS-28093] Reverting getDownloadableId from #1563. Not compatible.

core/src/main/java/hudson/tools/DownloadFromUrlInstaller.java

@@ -122,16 +122,15 @@ public abstract class DownloadFromUrlInstaller extends ToolInstaller {
         }
 
         protected Downloadable createDownloadable() {
-            return new Downloadable(getDownloadableId());
+            return new Downloadable(getId());
         }
 
         /**
          * This ID needs to be unique, and needs to match the ID token in the JSON update file.
          * <p>
          * By default we use the fully-qualified class name of the {@link DownloadFromUrlInstaller} subtype.
-         * @since 1.610
          */
-        public String getDownloadableId() {
+        public String getId() {
             return clazz.getName().replace('$','.');
         }
 
@@ -145,7 +144,7 @@ public abstract class DownloadFromUrlInstaller extends ToolInstaller {
          * @return never null.
          */
         public List<? extends Installable> getInstallables() throws IOException {
-            JSONObject d = Downloadable.get(getDownloadableId()).getData();
+            JSONObject d = Downloadable.get(getId()).getData();
             if(d==null)     return Collections.emptyList();
             return Arrays.asList(((InstallableList)JSONObject.toBean(d,InstallableList.class)).list);
         }