static final boolean GENERATE_CANCELLATION_CAUSES;

  static {
    // System.getProperty may throw if the security policy does not permit access.
    boolean generateCancellationCauses;
    try {
      generateCancellationCauses =
          parseBoolean(System.getProperty("guava.concurrent.generate_cancellation_cause", "false"));
    } catch (SecurityException e) {

  private static final class Cancellation {
    // constants to use when GENERATE_CANCELLATION_CAUSES = false
    static final @Nullable Cancellation CAUSELESS_INTERRUPTED;
    static final @Nullable Cancellation CAUSELESS_CANCELLED;

    static {
      if (GENERATE_CANCELLATION_CAUSES) {
        CAUSELESS_CANCELLED = null;
        CAUSELESS_INTERRUPTED = null;
      } else {