shadows/framework/src/main/java/org/robolectric/shadows/ShadowProcess.java
@Implementation
  protected static final int getThreadPriority(int tid) {
    if (tid == 0) {
      tid = ShadowProcess.myTid();
    }
    synchronized (threadPrioritiesLock) {
      return threadPriorities.getOrDefault(tid, 0);
    }
  }
@Implementation
  protected static final int getThreadPriority(int tid) {
    if (tid == 0) {
      tid = ShadowProcess.myTid();
    }
    synchronized (threadPrioritiesLock) {
      return threadPriorities.getOrDefault(tid, 0);
    }
  }
Returns priority stored for the given thread.

@param tid The identifier of the thread. If equals zero, the identifier of the calling thread
will be used.