* case we ever switch to JUnit 4:
               */
              fail();
            }
          }
        });
  }

  // TODO(cpovirk): promote to Uninterruptibles, and add untimed version
  private static void joinUninterruptibly(Thread thread, long timeout, TimeUnit unit) {
    boolean interrupted = false;
    try {
      long remainingNanos = unit.toNanos(timeout);

               * case we ever switch to JUnit 4:
               */
              fail();
            }
          }
        });
  }

  // TODO(cpovirk): promote to Uninterruptibles, and add untimed version
  private static void joinUninterruptibly(Thread thread, long timeout, TimeUnit unit) {
    boolean interrupted = false;
    try {
      long remainingNanos = unit.toNanos(timeout);

    } else if (isTryEnter(method)) {
      assertFalse(desc, isTimed(method));
      assertTrue(desc, isBoolean(method));
      assertFalse(desc, isInterruptible(method));
    } else if (isWaitFor(method)) {
      assertTrue(desc, isGuarded(method));
      assertEquals(desc, isTimed(method), isBoolean(method));
    } else { // any other enterXxx method
      assertEquals(desc, isTimed(method), isBoolean(method));
    }
  }

When working on some source code it is important to be aware of the runtimes in which it will run, so that you don't break these constraints.
There is some assistance in the IDE for this plus a lot of validation that is applied at build time and on CI, but it is useful to keep these constraints in mind as well.

See [Gradle runtimes](runtimes.md) for a list of these runtimes and more details.

### Build execution model

      return "SynchronizedHelper";
    }
  }

  private static boolean mightBeAndroid() {
    String runtime = System.getProperty("java.runtime.name", "");
    // I have no reason to believe that `null` is possible here, but let's make sure we don't crash:
    return runtime == null || runtime.contains("Android");
  }

@REM   MAVEN_BATCH_ECHO  (Optional) Set to 'on' to enable the echoing of the batch commands.
@REM   MAVEN_BATCH_PAUSE (Optional) set to 'on' to wait for a key stroke before ending.
@REM   MAVEN_OPTS        (Optional) Java runtime options used when Maven is executed.
@REM   MAVEN_SKIP_RC     (Optional) Flag to disable loading of mavenrc files.
@REM -----------------------------------------------------------------------------

# Environment Variable Prerequisites
#
#   JAVA_HOME           (Optional) Points to a Java installation.
#   MAVEN_ARGS          (Optional) Arguments passed to Maven before CLI arguments.
#   MAVEN_OPTS          (Optional) Java runtime options used when Maven is executed.
#   MAVEN_SKIP_RC       (Optional) Flag to disable loading of mavenrc files.

    // e.g. using Thread#activeCount()
    return max(10L, Runtime.getRuntime().totalMemory() / (32L * 1024L * 1024L));
  }

  /**
   * Waits until the given future {@linkplain Future#isDone is done}, invoking the garbage collector
   * as necessary to try to ensure that this will happen.
   *
   * @throws RuntimeException if timed out or interrupted while waiting
   */
  @SuppressWarnings("removal") // b/260137033

    // e.g. using Thread#activeCount()
    return max(10L, Runtime.getRuntime().totalMemory() / (32L * 1024L * 1024L));
  }

  /**
   * Waits until the given future {@linkplain Future#isDone is done}, invoking the garbage collector
   * as necessary to try to ensure that this will happen.
   *
   * @throws RuntimeException if timed out or interrupted while waiting
   */
  @SuppressWarnings("removal") // b/260137033

            runtime.registerData("eolLink", getHelpUrl(eolLink));
        }
    }

    /**
     * Sets up search HTML data for a given action.
     *
     * @param action  The action to set up data for.
     * @param runtime The action runtime.
     */
    public void setupSearchHtmlData(final TypicalAction action, final ActionRuntime runtime) {