public static int computeInt32SizeNoTag(final int value)
    {
        if (value >= 0)
        {
            return computeRawVarint32Size(value);
        }
        else
        {
            // Must sign-extend.
            return 10;
        }
    }
Compute the number of bytes that would be needed to encode an {@code int32} field, including tag.
protostuff-core/src/test/java/io/protostuff/CodedOutput.java