CompositeMetadataCodec { public static boolean isWellKnownMimeType(ByteBuf header) { return header.readableBytes() == 1; } private  CompositeMetadataCodec(); static int computeNextEntryIndex(
      int currentEntryIndex, ByteBuf headerSlice, ByteBuf contentSlice); static ByteBuf[] decodeMimeAndContentBuffersSlices(
      ByteBuf compositeMetadata, int entryIndex, boolean retainSlices); static byte decodeMimeIdFromMimeBuffer(ByteBuf mimeBuffer); @Nullable static CharSequence decodeMimeTypeFromMimeBuffer(ByteBuf flyweightMimeBuffer); static void encodeAndAddMetadata(
      CompositeByteBuf compositeMetaData,
      ByteBufAllocator allocator,
      String customMimeType,
      ByteBuf metadata); static void encodeAndAddMetadata(
      CompositeByteBuf compositeMetaData,
      ByteBufAllocator allocator,
      WellKnownMimeType knownMimeType,
      ByteBuf metadata); static void encodeAndAddMetadataWithCompression(
      CompositeByteBuf compositeMetaData,
      ByteBufAllocator allocator,
      String mimeType,
      ByteBuf metadata); static boolean hasEntry(ByteBuf compositeMetadata, int entryIndex); static boolean isWellKnownMimeType(ByteBuf header);  }
@Test void isWellKnownMimeType() { ByteBuf wellKnown = Unpooled.buffer().writeByte(0); assertThat(CompositeMetadataCodec.isWellKnownMimeType(wellKnown)).isTrue(); ByteBuf explicit = Unpooled.buffer().writeByte(2).writeChar('a'); assertThat(CompositeMetadataCodec.isWellKnownMimeType(explicit)).isFalse(); }