Fix accidentally mutable (although private) fields

Signed-off-by: Felipe <afrueda97@outlook.com>

Author: afrueda97

analyzer/java/com/engflow/bazel/invocation/analyzer/bazelprofile/ProfileThread.java

@@ -38,8 +38,8 @@
 public class ProfileThread {
   private final ThreadId threadId;
 
-  @Nullable private String name;
-  @Nullable private Integer sortIndex;
+  @Nullable private final String name;
+  @Nullable private final Integer sortIndex;
 
   private final ImmutableList<JsonObject> extraMetadata;
   private final ImmutableList<JsonObject> extraEvents;