Ela é apenas uma extensão do OAuth2 especificando algumas coisas que são relativamente ambíguas no OAuth2, para tentar torná-lo mais interoperável.

Por exemplo, o login do Google usa OpenID Connect (que por baixo dos panos usa OAuth2).

Mas o login do Facebook não tem suporte para OpenID Connect. Ele tem a própria implementação do OAuth2.

### OpenID (não "OpenID Connect")

 * difference. A CharEscaper can only process Java <a
 * href="http://en.wikipedia.org/wiki/UTF-16">UTF16</a> characters in isolation and may not cope
 * when it encounters surrogate pairs. This class facilitates the correct escaping of all Unicode
 * characters.
 *
 * <p>As there are important reasons, including potential security issues, to handle Unicode

 * difference. A CharEscaper can only process Java <a
 * href="http://en.wikipedia.org/wiki/UTF-16">UTF16</a> characters in isolation and may not cope
 * when it encounters surrogate pairs. This class facilitates the correct escaping of all Unicode
 * characters.
 *
 * <p>As there are important reasons, including potential security issues, to handle Unicode

        // Check encoded name (TEST -> encoded as pairs)
        // T = 0x54 -> upper nibble: 0x5 -> 0x46 (F), lower nibble: 0x4 -> 0x45 (E)
        assertEquals('F', dst[1]); // (0x54 >> 4) + 0x41 = 0x46 = 'F'
        assertEquals('E', dst[2]); // (0x54 & 0x0F) + 0x41 = 0x45 = 'E'

        // Check padding (positions 8-30 should be 'CA' pairs for spaces)
        for (int i = 8; i < 31; i += 2) {

  }

  @LazyInit @RetainedWith private transient @Nullable ImmutableSetMultimap<V, K> inverse;

  /**
   * {@inheritDoc}
   *
   * <p>Because an inverse of a set multimap cannot contain multiple pairs with the same key and
   * value, this method returns an {@code ImmutableSetMultimap} rather than the {@code
   * ImmutableMultimap} specified in the {@code ImmutableMultimap} class.
   */
  @Override

    }
  }
  return commaFound
}

private fun Buffer.startsWith(prefix: Byte): Boolean = !exhausted() && this[0] == prefix

/**
 * Reads a double-quoted string, unescaping quoted pairs like `\"` to the 2nd character in each
 * sequence. Returns the unescaped string, or null if the buffer isn't prefixed with a
 * double-quoted string.
 */
@Throws(EOFException::class)

 *
 * <p>When iterating through the collections supplied by this class, the ordering of values for a
 * given key agrees with the order in which the values were added.
 *
 * <p>This multimap allows duplicate key-value pairs. After adding a new key-value pair equal to an
 * existing key-value pair, the {@code ArrayListMultimap} will contain entries for both the new
 * value and the old value.
 *

    /**
     * Parses client rule configuration string into a list of client name and pattern pairs.
     * The configuration string format is "clientName:pattern,clientName:pattern,..."
     * Results are cached to improve performance on subsequent calls.
     *
     * @param value the client rule configuration string
     * @return a list of pairs containing client names and their corresponding compiled patterns
     */

import org.jspecify.annotations.Nullable;

/**
 * A {@code SetMultimap} whose set of values for a given key are kept sorted; that is, they comprise
 * a {@link SortedSet}. It cannot hold duplicate key-value pairs; adding a key-value pair that's
 * already in the multimap has no effect. This interface does not specify the ordering of the
 * multimap's keys. See the {@link Multimap} documentation for information common to all multimaps.
 *

            if (codes[i] == code) {
                return Optional.of(msgs[i]);
            }
        }
        return Optional.empty();
    }

    // Producer for code->message pairs covering all known constants (happy path)
    static Stream<Arguments> knownCodeMessagePairs() {
        return Stream.of(Arguments.of(WinError.ERROR_SUCCESS, "The operation completed successfully."),