@NotNull
  @Override
  public Collection<DebuggerSession> getSessions() {
    synchronized (mySessions) {
      final Collection<DebuggerSession> values = mySessions.values();
      return values.isEmpty() ? Collections.emptyList() : new ArrayList<>(values);
    }
  }
@NotNull
  @Override
  public Collection<DebuggerSession> getSessions()