code: @Deprecated
      public static ByteBuf unmodifiableBuffer(ByteBuf buffer) {
          ByteOrder endianness = buffer.order();
          if (endianness == BIG_ENDIAN) {
              return new ReadOnlyByteBuf(buffer);
          }
  
          return new ReadOnlyByteBuf(buffer.order(BIG_ENDIAN)).order(LITTLE_ENDIAN);
      }
docs: Creates a read-only buffer which disallows any modification operations
  on the specified {@code buffer}.  The new buffer has the same
  {@code readerIndex} and {@code writerIndex} with the specified
  {@code buffer}.
  
  @deprecated Use {@link ByteBuf#asReadOnly()}.