Communicate persistent worker protocol to remote execution service

This gives remote execution services the information required to
correctly handle remote persistent workers that do not use the default
protocol.

Closes #28405.

RELNOTES: The `requires-worker-protocol` execution requirement is now
forwarded to remote execution services as a platform property to support
intermixing JSON and Proto remote persistent worker protocols across a
build.

Author: armandomontanez

src/main/java/com/google/devtools/build/lib/remote/RemoteExecutionService.java

@@ -528,13 +528,17 @@ public RemoteAction buildRemoteAction(
 
       // Get the remote platform properties.
       Platform platform;
+      ImmutableMap.Builder<String, String> additionalPropertiesBuilder = ImmutableMap.builder();
       if (toolSignature != null) {
-        platform =
-            PlatformUtils.getPlatformProto(
-                spawn, remoteOptions, ImmutableMap.of("persistentWorkerKey", toolSignature.key));
-      } else {
-        platform = PlatformUtils.getPlatformProto(spawn, remoteOptions);
+        additionalPropertiesBuilder.put("persistentWorkerKey", toolSignature.key);
+      }
+      if (spawn.getExecutionInfo().containsKey(ExecutionRequirements.REQUIRES_WORKER_PROTOCOL)) {
+        additionalPropertiesBuilder.put(
+          ExecutionRequirements.REQUIRES_WORKER_PROTOCOL,
+          spawn.getExecutionInfo().get(ExecutionRequirements.REQUIRES_WORKER_PROTOCOL));
       }
+      platform =
+          PlatformUtils.getPlatformProto(spawn, remoteOptions, additionalPropertiesBuilder.build());
 
       SpawnScrubber spawnScrubber = scrubber != null ? scrubber.forSpawn(spawn) : null;
       Command command =

src/test/java/com/google/devtools/build/lib/remote/RemoteExecutionServiceTest.java

@@ -2636,6 +2636,7 @@ public void buildRemoteActionForRemotePersistentWorkers(
     Spawn spawn =
         new SpawnBuilder("@flagfile")
             .withExecutionInfo(ExecutionRequirements.SUPPORTS_WORKERS, "1")
+            .withExecutionInfo(ExecutionRequirements.REQUIRES_WORKER_PROTOCOL, "json")
             .withInputs(input, toolInput, runfilesArtifact)
             .withTools(toolInput, runfilesArtifact)
             .setPathMapper(
@@ -2726,10 +2727,16 @@ public void buildRemoteActionForRemotePersistentWorkers(
                 (byte[]) merkleTree.blobs().get(merkleTree.digest()),
                 ExtensionRegistry.getEmptyRegistry()))
         .isEqualTo(rootDirectory);
-    assertThat(remoteAction1.getAction().getPlatform().getPropertiesList()).hasSize(1);
+    assertThat(remoteAction1.getAction().getPlatform().getPropertiesList()).hasSize(2);
     assertThat(remoteAction1.getAction().getPlatform().getProperties(0).getName())
         .isEqualTo("persistentWorkerKey");
 
+    // Ensure the worker protocol is communicated.
+    assertThat(remoteAction1.getAction().getPlatform().getProperties(1).getName())
+        .isEqualTo("requires-worker-protocol");
+    assertThat(remoteAction1.getAction().getPlatform().getProperties(1).getValue())
+        .isEqualTo("json");
+
     // Check that if a non-tool input changes, the persistent worker key does not change.
     fakeFileCache.createScratchInput(input, "value2");
     var remoteAction2 = service.buildRemoteAction(spawn, context);
@@ -2739,7 +2746,7 @@ public void buildRemoteActionForRemotePersistentWorkers(
     // Check that if a tool input changes, the persistent worker key changes.
     fakeFileCache.createScratchInput(toolInput, "worker value2");
     var remoteAction3 = service.buildRemoteAction(spawn, context);
-    assertThat(remoteAction3.getAction().getPlatform().getPropertiesList()).hasSize(1);
+    assertThat(remoteAction3.getAction().getPlatform().getPropertiesList()).hasSize(2);
     assertThat(remoteAction3.getAction().getPlatform().getProperties(0).getName())
         .isEqualTo("persistentWorkerKey");
     assertThat(remoteAction3.getAction().getPlatform().getProperties(0).getValue())