return longBitsToDouble(significand | ONE_BITS);
  }

  static double bigToDouble(BigInteger x) {
    // This is an extremely fast implementation of BigInteger.doubleValue(). JDK patch pending.
    BigInteger absX = x.abs();
    int exponent = absX.bitLength() - 1;
    // exponent == floor(log2(abs(x)))
    if (exponent < Long.SIZE - 1) {
      return x.longValue();

      try {
        // 1.8, 9, 10, 11, 12 etc
        val version = jvmVersion.toInt()
        if (version >= 9) return null
      } catch (_: NumberFormatException) {
        // expected on >= JDK 9
      }

      // Find Jetty's ALPN extension for OpenJDK.
      try {
        val alpnClassName = "org.eclipse.jetty.alpn.ALPN"
        val alpnClass = Class.forName(alpnClassName, true, null)

 with its <<<DefaultToolchainManagerPrivate>>> implementation ({{{./xref/org/apache/maven/toolchain/DefaultToolchainManagerPrivate.html}source}}),
 to manage toolchain selection,

 * internal JDK toolchain implementation: <<<JavaToolchain>>> interface ({{{./apidocs/org/apache/maven/toolchain/java/JavaToolchain.html}javadoc}}),
 with its <<<JavaToolchainImpl>>> implementation

  @GwtIncompatible // NullPointerTester
  public void testNulls() throws NoSuchMethodException {
    NullPointerTester tester = new NullPointerTester();
    // Necessary until JDK15:
    // https://bugs.openjdk.org/browse/JDK-8202469
    tester.ignore(Equivalence.class.getMethod("wrap", Object.class));

    tester.testAllPublicStaticMethods(Equivalence.class);
    tester.testAllPublicInstanceMethods(Equivalence.equals());

	set JVM_DLL=\bin\server\jvm.dll
	goto foundJVM
)

rem Fallback to 'client' JRE
if exist "%JAVA_HOME%"\bin\client\jvm.dll (
	set JVM_DLL=\bin\client\jvm.dll
	echo Warning: JAVA_HOME points to a JRE and not JDK installation; a client (not a server^) JVM will be used...
) else (
	echo JAVA_HOME points to an invalid Java installation (no jvm.dll found in "%JAVA_HOME%"^). Exiting...
	goto:eof
)

:foundJVM

   * of Java 20, it always throws an exception, and as of Java 26, the method does not even exist.
   * For now, we continue using it to clean up under older JDKs.
   *
   * Our usages should at least be *relatively* safe: Typically, threads started by a test are dying
   * at the end of the test, so there is no object state put at risk by stopping the threads

 * here. Cipher suites that are not available on either Android (through API level 24) or Java
 * (through JDK 9) are omitted for brevity.
 *
 * See [Android SSLEngine][sslengine] which lists the cipher suites supported by Android.
 *
 * See [JDK Providers][oracle_providers] which lists the cipher suites supported by Oracle.
 *

    Throwable thrownReflectionFailure = null;
    try {
      helper = new SafeAtomicHelper();
    } catch (Throwable reflectionFailure) { // sneaky checked exception
      // Some Android 5.0.x Samsung devices have bugs in JDK reflection APIs that cause
      // getDeclaredField to throw a NoSuchFieldException when the field is definitely there.
      // For these users fallback to a suboptimal implementation, based on synchronized. This will

   * application class loader.
   *
   * NOTE: The tests for this behavior (FinalizableReferenceQueueClassLoaderUnloadingTest) fail
   * strangely when run in JDK 9. We are considering this a known issue. Please see
   * https://github.com/google/guava/issues/3086 for more information.
   */

            validator.accept(pa.getValue());
            stk.pop();
            stk.pop();
        });
        root.map(Activation::getJdk).ifPresent(jdk -> {
            stk.push(new ActivationFrame("jdk", Optional.empty()));
            validator.accept(jdk);
            stk.pop();
        });
    }

    private void validate20RawPlugins(
            ModelProblemCollector problems,