On read, deflated block size is always reported as full buffer size

[abyrd]

During VEX format reads, the block size is always reported as the full buffer size.
Perhaps java.util.zip.Inflater#inflate(byte[], int, int) always fills the whole output buffer.

21:43:45.492 [Thread-1] DEBUG com.conveyal.osmlib.VEXBlock - Read block of 2097152 bytes.
21:43:45.492 [Thread-1] DEBUG com.conveyal.osmlib.VEXBlock - Contained 225787 entities with type 0.
21:43:45.620 [Thread-0] DEBUG com.conveyal.osmlib.VEXBlock - Wrote block of 1334622 bytes.
21:43:45.620 [Thread-0] DEBUG com.conveyal.osmlib.VEXBlock - Contained 241566 entities with type 0.
21:43:45.620 [main] INFO  com.conveyal.osmlib.VexInput - Processed 9960 blocks
21:43:45.636 [Thread-1] DEBUG com.conveyal.osmlib.VEXBlock - Read block of 2097152 bytes.
21:43:45.636 [Thread-1] DEBUG com.conveyal.osmlib.VEXBlock - Contained 216809 entities with type 0.
21:43:45.762 [Thread-0] DEBUG com.conveyal.osmlib.VEXBlock - Wrote block of 1279096 bytes.
21:43:45.762 [Thread-0] DEBUG com.conveyal.osmlib.VEXBlock - Contained 240155 entities with type 0.

[abyrd]

After inflater.finished() is true, both the pos variable being incremented in the loop and the inflater's internal bytes written counter will both equal the full size of the output buffer. This appears to be intentional behavior of inflate().

How can we get the true size of the decompressed data?