hpack/src/main/java/com/twitter/hpack/Encoder.java
private HeaderEntry getEntry(byte[] name, byte[] value) {
    if (length() == 0 || name == null || value == null) {
      return null;
    }
    int h = hash(name);
    int i = index(h);
    for (HeaderEntry e = headerFields[i]; e != null; e = e.next) {
      if (e.hash == h &&
          HpackUtil.equals(name, e.name) &&
          HpackUtil.equals(value, e.value)) {
        return e;
      }
    }
    return null;
  }
private HeaderEntry getEntry(byte[] name, byte[] value) {
    if (length() == 0 || name == null || value == null) {
      return null;
    }
    int h = hash(name);
    int i = index(h);
    for (HeaderEntry e = headerFields[i]; e != null; e = e.next) {
      if (e.hash == h &&
          HpackUtil.equals(name, e.name) &&
          HpackUtil.equals(value, e.value)) {
        return e;
      }
    }
    return null;
  }
Returns the header entry with the lowest index value for the header field.
Returns null if header field is not in the dynamic table.