Grow the buffer by adding a contiguous range of capacity in a single segment. This adds
minByteCount bytes but may add up to a full segment of additional capacity.
minByteCount bytes are available in the buffer’s current tail segment that will
be used; otherwise another segment will be allocated and appended. In either case this
returns the number of bytes of capacity added to this buffer.
Warning: it is the caller’s responsibility to either write new data to every byte of the newly-allocated capacity, or to shrink the buffer to the data written. Failure to do so may cause serious security problems as the data in the returned buffers is not zero filled. Buffers may contain dirty pooled segments that hold very sensitive data from other parts of the current process.
minByteCount - the size of the contiguous capacity. Must be positive and not greater
than the capacity size of a single segment (8 KiB).
the number of bytes expanded by. Not less than