@Override
    public int available() {
        return decompressedBuffer == null ? 0 : decompressedBuffer.remaining();
    }
Decompresses (if necessary) buffered data, optionally computes and validates a XXHash32 checksum, and writes the
result to a buffer.

@throws IOException
clients/src/main/java/org/apache/kafka/common/compress/Lz4BlockInputStream.java