Address PR review: fix hash truncation, antlrVersion API, immutability, and tests

- Hash full 32-bit ints in grammarHash to avoid collisions with ANTLR 4.13.2 ATN serialization
- Use RuntimeMetaData.getRuntimeVersion() instead of unreliable JAR manifest lookup
- Make GrammarBundle immutable with @value instead of @DaTa
- Update THIRD-PARTY to reflect ANTLR 4.13.2
- Harden tests with JSON parsing and add antlrVersion assertion

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Signed-off-by: Eric Wei <mengwei.eric@gmail.com>

Author: mengweieric

THIRD-PARTY

@@ -467,15 +467,15 @@ DAMAGE.
 
 ------
 
-** ANTLR; version 4.7.1 -- https://github.com/antlr/antlr4
+** ANTLR; version 4.13.2 -- https://github.com/antlr/antlr4
 /*
- * Copyright (c) 2012-2017 The ANTLR Project. All rights reserved.
+ * Copyright (c) 2012-2024 The ANTLR Project. All rights reserved.
  * Use of this file is governed by the BSD 3-clause license that
  * can be found in the LICENSE.txt file in the project root.
  */
 
 [The "BSD 3-clause license"]
-Copyright (c) 2012-2017 The ANTLR Project. All rights reserved.
+Copyright (c) 2012-2024 The ANTLR Project. All rights reserved.
 
 Redistribution and use in source and binary forms, with or without
 modification, are permitted provided that the following conditions

plugin/src/test/java/org/opensearch/sql/plugin/rest/RestPPLGrammarActionTest.java

@@ -12,6 +12,7 @@
 
 import java.io.IOException;
 import java.util.concurrent.atomic.AtomicInteger;
+import org.json.JSONObject;
 import org.junit.Before;
 import org.junit.Test;
 import org.opensearch.common.io.stream.BytesStreamOutput;
@@ -67,16 +68,31 @@ public void testGetGrammar_ReturnsBundle() throws Exception {
     assertEquals("Should return 200 OK", RestStatus.OK, response.status());
 
     String content = response.content().utf8ToString();
-    assertTrue(content.contains("\"bundleVersion\":\"1.0\""));
-    assertTrue(content.contains("\"antlrVersion\":"));
-    assertTrue(content.contains("\"grammarHash\":\"sha256:"));
-    assertTrue(content.contains("\"startRuleIndex\":0"));
-    assertTrue(content.contains("\"lexerSerializedATN\":"));
-    assertTrue(content.contains("\"parserSerializedATN\":"));
-    assertTrue(content.contains("\"lexerRuleNames\":"));
-    assertTrue(content.contains("\"parserRuleNames\":"));
-    assertTrue(content.contains("\"literalNames\":"));
-    assertTrue(content.contains("\"symbolicNames\":"));
+    JSONObject json = new JSONObject(content);
+
+    // Identity & versioning
+    assertEquals("1.0", json.getString("bundleVersion"));
+    assertTrue(
+        "antlrVersion should be a version string",
+        json.getString("antlrVersion").matches("\\d+\\.\\d+.*"));
+    assertTrue(
+        "grammarHash should start with sha256:",
+        json.getString("grammarHash").startsWith("sha256:"));
+    assertEquals(0, json.getInt("startRuleIndex"));
+
+    // Lexer ATN & metadata (non-empty arrays)
+    assertTrue(json.getJSONArray("lexerSerializedATN").length() > 0);
+    assertTrue(json.getJSONArray("lexerRuleNames").length() > 0);
+    assertTrue(json.getJSONArray("channelNames").length() > 0);
+    assertTrue(json.getJSONArray("modeNames").length() > 0);
+
+    // Parser ATN & metadata (non-empty arrays)
+    assertTrue(json.getJSONArray("parserSerializedATN").length() > 0);
+    assertTrue(json.getJSONArray("parserRuleNames").length() > 0);
+
+    // Vocabulary (non-empty arrays)
+    assertTrue(json.getJSONArray("literalNames").length() > 0);
+    assertTrue(json.getJSONArray("symbolicNames").length() > 0);
   }
 
   @Test

ppl/src/main/java/org/opensearch/sql/ppl/autocomplete/GrammarBundle.java

@@ -6,11 +6,11 @@
 package org.opensearch.sql.ppl.autocomplete;
 
 import lombok.Builder;
-import lombok.Data;
 import lombok.NonNull;
+import lombok.Value;
 
 /** Serialized ANTLR grammar data served by {@code GET /_plugins/_ppl/_grammar}. */
-@Data
+@Value
 @Builder
 public class GrammarBundle {
 

ppl/src/main/java/org/opensearch/sql/ppl/autocomplete/PPLGrammarBundleBuilder.java

@@ -17,15 +17,10 @@
 
 /** Builds the {@link GrammarBundle} for the PPL language from the generated ANTLR lexer/parser. */
 public class PPLGrammarBundleBuilder {
-  private static final String ANTLR_VERSION = getAntlrVersion();
+  private static final String ANTLR_VERSION =
+      org.antlr.v4.runtime.RuntimeMetaData.getRuntimeVersion();
   private static final String BUNDLE_VERSION = "1.0";
 
-  private static String getAntlrVersion() {
-    Package antlrPackage = org.antlr.v4.runtime.RuntimeMetaData.class.getPackage();
-    String version = antlrPackage.getImplementationVersion();
-    return version != null ? version : "unknown";
-  }
-
   public GrammarBundle build() {
     OpenSearchPPLLexer lexer = new OpenSearchPPLLexer(CharStreams.fromString(""));
     CommonTokenStream tokens = new CommonTokenStream(lexer);
@@ -62,14 +57,8 @@ public GrammarBundle build() {
   private static String computeGrammarHash(int[] lexerATN, int[] parserATN) {
     try {
       MessageDigest digest = MessageDigest.getInstance("SHA-256");
-      for (int v : lexerATN) {
-        digest.update((byte) (v >> 8));
-        digest.update((byte) v);
-      }
-      for (int v : parserATN) {
-        digest.update((byte) (v >> 8));
-        digest.update((byte) v);
-      }
+      updateDigest(digest, lexerATN);
+      updateDigest(digest, parserATN);
       digest.update(ANTLR_VERSION.getBytes(StandardCharsets.UTF_8));
       byte[] hash = digest.digest();
       // Output is always "sha256:" (7 chars) + 64 hex chars = 71 chars.
@@ -83,4 +72,13 @@ private static String computeGrammarHash(int[] lexerATN, int[] parserATN) {
       throw new IllegalStateException("SHA-256 not available", e);
     }
   }
+
+  private static void updateDigest(MessageDigest digest, int[] data) {
+    for (int v : data) {
+      digest.update((byte) (v >>> 24));
+      digest.update((byte) (v >>> 16));
+      digest.update((byte) (v >>> 8));
+      digest.update((byte) (v));
+    }
+  }
 }

ppl/src/test/java/org/opensearch/sql/ppl/autocomplete/PPLGrammarBundleBuilderTest.java

@@ -31,6 +31,15 @@ public void bundleVersionIsSet() {
     assertEquals("1.0", bundle.getBundleVersion());
   }
 
+  @Test
+  public void antlrVersionIsSet() {
+    String version = bundle.getAntlrVersion();
+    assertNotNull("antlrVersion should not be null", version);
+    assertTrue(
+        "antlrVersion should look like a version string, got: " + version,
+        version.matches("\\d+\\.\\d+.*"));
+  }
+
   @Test
   public void grammarHashHasExpectedFormat() {
     String hash = bundle.getGrammarHash();