}

  private static final Function<Object, Optional<?>> NULLABLE_TO_OPTIONAL =
      new Function<Object, Optional<?>>() {
        @Override
        public Optional<?> apply(@Nullable Object obj) {
          return Optional.fromNullable(obj);
        }
      };

  private static final Function<Optional<?>, @Nullable Object> OPTIONAL_TO_NULLABLE =
      new Function<Optional<?>, @Nullable Object>() {
        @Override

    ) : Closeable by body

    internal companion object {
      /** These options follow the boundary. */
      val afterBoundaryOptions =
        Options.of(
          // 0.  "\r\n"  More parts.
          "\r\n".encodeUtf8(),
          // 1.  "--"    No more parts.
          "--".encodeUtf8(),
          // 2.  " "     Optional whitespace. Only used if there are more parts.
          " ".encodeUtf8(),

   * analysis that that means "plain {@code T}" rather than the inferred type {@code @Nullable T}.
   * (And even if annotations on local variables were permitted as an optional hint, no annotation
   * would be the right tool for the job here: {@code @Nullable} is the annotation that we're trying
   * to get rid of, and {@code @NonNull} would be wrong for our use case for the same reason as

   * analysis that that means "plain {@code T}" rather than the inferred type {@code @Nullable T}.
   * (And even if annotations on local variables were permitted as an optional hint, no annotation
   * would be the right tool for the job here: {@code @Nullable} is the annotation that we're trying
   * to get rid of, and {@code @NonNull} would be wrong for our use case for the same reason as

        in flux. This can make the feature you're suggesting much clearer to us.

  - type: textarea
    attributes:
      label: (Optional) What would the method signatures for your feature look like?
      placeholder: |
        e.g.,
        public static <E> ImmutableList<E> of();
        public static <E> ImmutableList<E> of(E element);

   * analysis that that means "plain {@code T}" rather than the inferred type {@code @Nullable T}.
   * (And even if annotations on local variables were permitted as an optional hint, no annotation
   * would be the right tool for the job here: {@code @Nullable} is the annotation that we're trying
   * to get rid of, and {@code @NonNull} would be wrong for our use case for the same reason as

   * analysis that that means "plain {@code T}" rather than the inferred type {@code @Nullable T}.
   * (And even if annotations on local variables were permitted as an optional hint, no annotation
   * would be the right tool for the job here: {@code @Nullable} is the annotation that we're trying
   * to get rid of, and {@code @NonNull} would be wrong for our use case for the same reason as

import java.util.Map;
import java.util.regex.Pattern;

import org.codelibs.core.lang.StringUtil;
import org.codelibs.core.stream.StreamUtil;
import org.codelibs.fess.Constants;
import org.dbflute.optional.OptionalThing;

/**
 * Utility class for managing field configurations with parameter mappings.
 * This class provides functionality to retrieve and manage field-specific configurations
 * from a parameter map.
 */

     * @param charset the character encoding to use for reading
     * @param bufferSize the maximum number of lines to keep in the buffer (0 to disable buffering)
     * @param outputCallback optional callback function to process each line (can be null)
     */
    public InputStreamThread(final InputStream is, final Charset charset, final int bufferSize, final Consumer<String> outputCallback) {

    throw new IllegalStateException("Optional.get() cannot be called on an absent value");
  }

  @Override
  public T or(T defaultValue) {
    return checkNotNull(defaultValue, "use Optional.orNull() instead of Optional.or(null)");
  }

  @SuppressWarnings("unchecked") // safe covariant cast
  @Override
  public Optional<T> or(Optional<? extends T> secondChoice) {
    return (Optional<T>) checkNotNull(secondChoice);
  }