*   mutation, which is not an actual risk because we use `synchronized`.
   * - Make `remaining` require a non-null `seq` argument. But this is a bit weird because the
   *   method, while it would avoid the instance field `seq` would still access the instance field
   *   `pos`.
   */

  @Override
  public synchronized int read(CharBuffer target) throws IOException {
    checkNotNull(target);
    checkOpen();

 *
 * <p><b>Warning:</b> The methods of {@code ForwardingBlockingDeque} forward <b>indiscriminately</b>
 * to the methods of the delegate. For example, overriding {@link #add} alone <b>will not</b> change
 * the behaviour of {@link #offer} which can lead to unexpected behaviour. In this case, you should
 * override {@code offer} as well, either providing your own implementation, or delegating to the

   * href="https://bugs.openjdk.org/browse/JDK-6409434">JDK-6409434</a> is fixed. It's unclear
   * whether nulls were to be permitted or forbidden, but presumably the eventual fix will be to
   * permit them, as it seems more likely that code would depend on that behavior than on the other.
   * Thus, we say the bug is in set(), which fails to support null.
   */
  @J2ktIncompatible

   *
   * <ul>
   *   <li>{@link #JAVA_EXT_DIRS} was deprecated in Java 8 and removed in Java 9. We have not
   *       confirmed whether it is available under older versions.
   *   <li>{@link #JAVA_COMPILER}, while still listed as required as of Java 15, is typically not
   *       available even under older version.
   *   <li>Any property may be cleared through APIs like {@link System#clearProperty}.

 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 */

 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *

 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *

 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *

 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *

 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *