import com.google.j2objc.annotations.RetainedWith;
import java.util.function.BiConsumer;
import org.jspecify.annotations.Nullable;

/**
 * Implementation of {@link ImmutableMap} with exactly one entry.
 *
 * @author Jesse Wilson
 * @author Kevin Bourrillion
 */
@GwtCompatible
@SuppressWarnings("serial") // uses writeReplace(), not default serialization

 * <p>
 * <strong>Thread-Safety:</strong> This class is <strong>NOT thread-safe</strong>.
 * It extends {@link LinkedHashMap} without synchronization. If multiple threads access
 * an instance concurrently, and at least one thread modifies the map structurally,
 * it must be synchronized externally.
 * </p>
 * <p>
 * For thread-safe usage, wrap with {@link java.util.Collections#synchronizedMap(Map)}:
 * </p>
 * <pre>

/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You under the Apache License, Version 2.0
 *  (the "License"); you may not use this file except in compliance with
 *  the License.  You may obtain a copy of the License at
 *

        // Demonstrate the bug when + is not escaped
        // In regex, + means "one or more" of the previous character
        String wrongPattern = "(application/xhtml+xml|application/rdf+xml)";
        Pattern pattern = Pattern.compile(wrongPattern);

        // Without escaping, "application/xhtml+xml" does NOT match
        // because the pattern expects "one or more 'l'" followed by "xml"

 * whether there is any data left is by trying to retrieve it. These types of data sources are
 * ordinarily difficult to write iterators for. But using this class, one must implement only the
 * {@link #computeNext} method, and invoke the {@link #endOfData} method when appropriate.
 *
 * <p>Another example is an iterator that skips over null elements in a backing iterator. This could

## Verification instructions

### Importing the key

You can import the key into your GPG keyring in one of two ways.

First, copy the public key block below into a new file called `gradle_pubkey.asc`, then import it with this command:

```bash
gpg --import gradle_pubkey.asc
```

    CharSource reader =
        new CharSource() {
          @Override
          public Reader openStream() throws IOException {
            if (counter[0]++ != 0) {
              throw new IllegalStateException("More than one source open");
            }
            return new FilterReader(source.openStream()) {
              @Override
              public void close() throws IOException {
                super.close();

   * parameter as non-nullable (since passing null to a FilenameFilter is unsafe in general), but if
   * someone still manages to pass null, let's continue to have the method work.
   *
   * (PatternFilenameFilter is of course one of those classes that shouldn't be a publicly visible
   * class to begin with but rather something returned from a static factory method whose declared

    this.readable = checkNotNull(readable);
    this.reader = (readable instanceof Reader) ? (Reader) readable : null;
  }

  /**
   * Reads a line of text. A line is considered to be terminated by any one of a line feed ({@code
   * '\n'}), a carriage return ({@code '\r'}), or a carriage return followed immediately by a
   * linefeed ({@code "\r\n"}).
   *

 * an {@code ArrayTable} concurrently and one of the threads modifies its value, there is no
 * guarantee that the new value will be fully visible to the other threads. To guarantee that
 * modifications are visible, synchronize access to the table. Unlike other {@code Table}
 * implementations, synchronization is unnecessary between a thread that writes to one cell and a
 * thread that reads from another.
 *