Drop stored scripts with the old style-id (#48078)

This PR fixes (#47593). Stored scripts with the old-style id of lang#id are 
saved through the upgrade process but are no longer accessible in recent 
versions. This fix will drop those scripts altogether since there is no way for 
a user to access them.

Author: jdconrad

server/src/main/java/org/elasticsearch/script/ScriptMetaData.java

@@ -249,7 +249,12 @@ public static ScriptMetaData fromXContent(XContentParser parser) throws IOExcept
                     source = StoredScriptSource.fromXContent(parser, true);
 
                     if (exists == null) {
-                        scripts.put(id, source);
+                        // due to a bug (https://github.com/elastic/elasticsearch/issues/47593)
+                        // scripts may have been retained during upgrade that include the old-style
+                        // id of lang#id; these scripts are unreachable after 7.0, so they are dropped
+                        if (id.contains("#") == false) {
+                            scripts.put(id, source);
+                        }
                     } else if (exists.getLang().equals(source.getLang()) == false) {
                         throw new IllegalArgumentException("illegal stored script, id [" + id + "] used for multiple scripts with " +
                             "different languages [" + exists.getLang() + "] and [" + source.getLang() + "]; scripts using the old " +

server/src/test/java/org/elasticsearch/script/ScriptMetaDataTests.java

@@ -32,6 +32,7 @@
 
 import java.io.IOException;
 import java.io.UncheckedIOException;
+import java.util.Collections;
 
 public class ScriptMetaDataTests extends AbstractSerializingTestCase<ScriptMetaData> {
 
@@ -168,6 +169,42 @@ public void testLoadEmptyScripts() throws IOException {
         assertWarnings("empty templates should no longer be used");
     }
 
+    public void testOldStyleDropped() throws IOException {
+        XContentBuilder builder = XContentBuilder.builder(XContentType.JSON.xContent());
+
+        builder.startObject();
+        {
+            builder.startObject("painless#test");
+            {
+                builder.field("lang", "painless");
+                builder.field("source", "code");
+            }
+            builder.endObject();
+            builder.startObject("lang#test");
+            {
+                builder.field("lang", "test");
+                builder.field("source", "code");
+            }
+            builder.endObject();
+            builder.startObject("test");
+            {
+                builder.field("lang", "painless");
+                builder.field("source", "code");
+            }
+            builder.endObject();
+        }
+        builder.endObject();
+
+        XContentParser parser = XContentType.JSON.xContent()
+                .createParser(NamedXContentRegistry.EMPTY, DeprecationHandler.THROW_UNSUPPORTED_OPERATION,
+                        BytesReference.bytes(builder).streamInput());
+        ScriptMetaData smd = ScriptMetaData.fromXContent(parser);
+        assertNull(smd.getStoredScript("painless#test"));
+        assertNull(smd.getStoredScript("lang#test"));
+        assertEquals(new StoredScriptSource("painless", "code", Collections.emptyMap()), smd.getStoredScript("test"));
+        assertEquals(1, smd.getStoredScripts().size());
+    }
+
     @Override
     protected boolean enableWarningsCheck() {
         return true;