private static int rawReadInt(ByteBuff input) {
    int b1 = Byte.toUnsignedInt(input.get());
    int b2 = Byte.toUnsignedInt(input.get());
    int b3 = Byte.toUnsignedInt(input.get());
    int b4 = Byte.toUnsignedInt(input.get());
    return ((b1 << 24) + (b2 << 16) + (b3 << 8) + b4);
  }
Read an integer from the buffer in big-endian byte order. Note that {@link ByteBuffer#getInt()}
reads in system-dependent endian-ness, so we can't use that.
hbase-common/src/main/java/org/apache/hadoop/hbase/io/compress/BlockDecompressorHelper.java