code: @Nullable
    public IMimeType getMimeTypeFromBytes (@Nullable final byte [] aBytes, @Nullable final IMimeType aDefault)
    {
      if (aBytes == null || aBytes.length == 0)
        return aDefault;
  
      return m_aRWLock.readLocked ( () -> {
        for (final MimeTypeContent aMTC : m_aMimeTypeContents)
          if (aMTC.matchesBeginning (aBytes))
            return aMTC.getMimeType ();
  
        // default fallback
        return aDefault;
      });
    }
docs: Try to determine the MIME type from the given byte array.
  
  @param aBytes
  The byte array to parse. May be <code>null</code> or empty.
  @param aDefault
  The default MIME type to be returned, if no matching MIME type was
  found. May be <code>null</code>.
  @return The supplied default value, if no matching MIME type was found. May
  be <code>null</code>.