Fix up activity token

Author: Quinn-With-Two-Ns

temporal-sdk/src/main/java/io/temporal/internal/nexus/OperationTokenType.java

@@ -6,7 +6,7 @@
 public enum OperationTokenType {
   UNKNOWN(0),
   WORKFLOW_RUN(1),
-  ACTIVITY_EXECUTION(4);
+  ACTIVITY_EXECUTION(2);
 
   private final int value;
 

temporal-sdk/src/main/java/io/temporal/internal/nexus/OperationTokenUtil.java

@@ -31,6 +31,9 @@ public static OperationToken loadOperationToken(String operationToken) {
     if (token.getVersion() != null && token.getVersion() != 0) {
       throw new IllegalArgumentException("Invalid operation token: unexpected version field");
     }
+    if (token.getType() == OperationTokenType.UNKNOWN) {
+      throw new IllegalArgumentException("Invalid operation token: unknown or missing type (t)");
+    }
     if (token.getType() == OperationTokenType.WORKFLOW_RUN
         && Strings.isNullOrEmpty(token.getWorkflowId())) {
       throw new IllegalArgumentException("Invalid operation token: missing workflow ID (wid)");

temporal-sdk/src/test/java/io/temporal/internal/nexus/WorkflowRunTokenTest.java

@@ -119,15 +119,15 @@ public void loadWorkflowIdFromBadOperationToken() {
                 encoder.encodeToString(badTokenUnknownVersion.getBytes())));
 
     // Bad token, unknown type (also has bad version, so loadOperationToken rejects on version)
-    String badTokenUnknownType = "{\"t\":4,\"ns\":\"namespace\", \"wid\":\"workflowId\", \"v\":1}";
+    String badTokenUnknownType = "{\"t\":2,\"ns\":\"namespace\", \"wid\":\"workflowId\", \"v\":1}";
     Assert.assertThrows(
         IllegalArgumentException.class,
         () ->
             OperationTokenUtil.loadOperationToken(
                 encoder.encodeToString(badTokenUnknownType.getBytes())));
 
     // Bad token, unknown type with valid version — loadWorkflowRunOperationToken rejects on type
-    String badTokenWrongType = "{\"t\":4,\"ns\":\"namespace\", \"wid\":\"workflowId\"}";
+    String badTokenWrongType = "{\"t\":2,\"ns\":\"namespace\", \"wid\":\"workflowId\"}";
     Assert.assertThrows(
         IllegalArgumentException.class,
         () ->