val value = cacheControl.toString()
  return when {
    value.isEmpty() -> removeHeader("Cache-Control")
    else -> header("Cache-Control", value)
  }
}

fun Request.Builder.commonGet(): Request.Builder = method("GET", null)

fun Request.Builder.commonHead(): Request.Builder = method("HEAD", null)

fun Request.Builder.commonPost(body: RequestBody): Request.Builder = method("POST", body)

    try {
      MessageDigest digest = MessageDigest.getInstance(algorithmName);
      assertEquals(
          HashCode.fromBytes(digest.digest(input)), ALGORITHMS.get(algorithmName).hashBytes(input));
      for (int bytes = 4; bytes <= digest.getDigestLength(); bytes++) {
        assertEquals(
            HashCode.fromBytes(Arrays.copyOf(digest.digest(input), bytes)),

      update(b.array(), b.arrayOffset() + b.position(), b.remaining());
      Java8Compatibility.position(b, b.limit());
    } else {
      for (int remaining = b.remaining(); remaining > 0; remaining--) {
        update(b.get());
      }
    }
  }

  /** Updates the sink with the given number of bytes from the buffer. */
  @CanIgnoreReturnValue
  private Hasher update(int bytes) {
    try {
      update(scratch.array(), 0, bytes);

    return map().size();
  }

  @Override
  public boolean contains(@CheckForNull Object object) {
    if (object instanceof Entry) {
      Entry<?, ?> entry = (Entry<?, ?>) object;
      V value = map().get(entry.getKey());
      return value != null && value.equals(entry.getValue());
    }
    return false;
  }

  @Override
  boolean isPartialView() {
    return map().isPartialView();
  }

            }
        }
        return false;
    }


    /**
     * 
     * @param pairs
     * @param type
     * @return first occurance of the given type
     */
    public static AvPair get ( List<AvPair> pairs, int type ) {
        Iterator<AvPair> it = pairs.iterator();
        while ( it.hasNext() ) {
            AvPair p = it.next();
            if ( p.getType() == type ) {
                return p;

                for ( KerberosKey key : keys ) {
                    keysByAlgo.put(key.getKeyType(), key);
                }

                KerberosKey serverKey = keysByAlgo.get(encType.getValue().intValue());
                if ( keysByAlgo.isEmpty() || serverKey == null ) {
                    throw new PACDecodingException("Kerberos key not found for eType " + encType.getValue());
                }

///

/// info

In this example we use invented custom headers `X-Key` and `X-Token`.

But in real cases, when implementing security, you would get more benefits from using the integrated [Security utilities (the next chapter)](../security/index.md){.internal-link target=_blank}.

///

## Dependencies errors and return values

        return (FileConfigCB) this;
    }

    @Override
    public void acceptPrimaryKeyMap(Map<String, ? extends Object> primaryKeyMap) {
        acceptPK((String) primaryKeyMap.get("_id"));
    }

    // ===================================================================================
    //                                                                               Build

    assertEquals(2, params.size());
    assertEquals(TypeToken.of(int.class), params.get(0).getType());
    assertEquals(TypeToken.of(String.class), params.get(1).getType());
  }

  public void testMethod_equals() throws NoSuchMethodException {
    Method getMethod = List.class.getMethod("get", int.class);
    Method setMethod = List.class.getMethod("set", int.class, Object.class);
    new EqualsTester()

        if( CACHE_POLICY == 0 ) {
            return;
        }
        synchronized( ADDRESS_CACHE ) {
            CacheEntry entry = (CacheEntry)ADDRESS_CACHE.get( hostName );
            if( entry == null ) {
                entry = new CacheEntry( hostName, addr, expiration );
                ADDRESS_CACHE.put( hostName, entry );
            } else {