*
     * Consequently:
     * 1. If the previous mean is finite and the new value is non-finite then the new mean is that
     *    value (whether it is NaN or infinity).
     * 2. If the new value is finite and the previous mean is non-finite then the mean is unchanged
     *    (whether it is NaN or infinity).
     * 3. If both the previous mean and the new value are non-finite and...

  /**
   * Maps the specified class to the specified value. Does <i>not</i> associate this value with any
   * of the class's supertypes.
   *
   * @return the value previously associated with this class (possibly {@code null}), or {@code
   *     null} if there was no previous entry.
   */
  @CanIgnoreReturnValue
  @CheckForNull
  <T extends B> T putInstance(Class<@NonNull T> type, @ParametricNullness T value);

But at some point, there was no other option than creating something that provided all these features, taking the best ideas from previous tools, and combining them in the best way possible, using language features that weren't even available before (Python 3.6+ type hints).

## Previous tools

### <a href="https://www.djangoproject.com/" class="external-link" target="_blank">Django</a>

		// request next fill to be prepared
		if s.end == maxInt {
			s.fillReq <- struct{}{}
		}
	}

	s.pos++
	return s.buf[s.ipos]
}

// back undoes a previous call to next(), moving backward one byte in the internal buffer.
// as we only guarantee a lookback buffer size of one, any subsequent calls to back()
// before calling next() may panic
func (s *scanner) back() {

    assertEquals("4", iterator.previous());
    assertEquals("3", iterator.previous());
    assertEquals("2", iterator.previous());
    assertTrue(iterator.hasPrevious());
    assertEquals("1", iterator.previous());
    assertFalse(iterator.hasPrevious());
    assertEquals(-1, iterator.previousIndex());
    try {
      iterator.previous();
      fail("did not detect beginning of list");

    assertEquals("4", iterator.previous());
    assertEquals("3", iterator.previous());
    assertEquals("2", iterator.previous());
    assertTrue(iterator.hasPrevious());
    assertEquals("1", iterator.previous());
    assertFalse(iterator.hasPrevious());
    assertEquals(-1, iterator.previousIndex());
    try {
      iterator.previous();
      fail("did not detect beginning of list");

     */
    void add(Problem.Severity severity, String message, int line, int column, Exception cause);

    /**
     * The next messages will be bound to this source. When calling this method again, previous messages keep
     * their source, but the next messages will use the new source.
     *
     * @param source a source
     */
    void setSource(String source);

    /**
     *

     */
    @Nonnull
    Optional<Source> locate(@Nonnull Path dir);

    /**
     * Parse the model obtained previously by a previous call to {@link #locate(Path)}.
     *
     * @param source the source to parse, never {@code null}
     * @param options possible parsing options, may be {@code null}

 */
public class KillLeakingJavaProcesses {
    enum ExecutionMode {
        /**
         * Run at the beginning of each build. Kill potentially leaked processes in previous builds.
         * Only kill local Gradle processes (classpath in checkout directory).
         * Not clean up global Gradle processes (i.e. classpath in ~/.gradle/...).
         */

  }

  private void addToCache(K key, V value) {
    addToCache(new CacheEntry<K, V>(key, value));
  }

  private void addToCache(CacheEntry<K, V> entry) {
    // Slide new entry into first cache position. Drop previous entry in second cache position.
    cacheEntry2 = cacheEntry1;
    cacheEntry1 = entry;
  }

  private static final class CacheEntry<K, V> {
    final K key;
    final V value;