okio: SegmentPool blocked

Hello,

I see a strange picture in a running jcmd Thread.print on my server app using okio 2.5.0, many threads are blocking during parallel decoding:

   java.lang.Thread.State: BLOCKED (on object monitor)
     at okio.SegmentPool.recycle(SegmentPool.kt:64)
    - waiting to lock <0x00000002cf4f3c78> (a okio.SegmentPool)

In source code for SegmentPool there are @ThreadLocal and synchronized(this) at the same time. So, how does that pool intended to work?