code: private synchronized void _release(@Nonnull FilePath p) {
          Entry old = inUse.get(p.getRemote());
          if (old==null)
              throw new AssertionError("Releasing unallocated workspace "+p);
          if (LOGGER.isLoggable(Level.FINE)) {
              LOGGER.log(Level.FINE, "releasing " + p + " with lock count " + old.lockCount, new Throwable("from " + this));
          }
          old.lockCount--;
          if (old.lockCount==0)
              inUse.remove(p.getRemote());
          notifyAll();
      }
docs: Releases an allocated or acquired workspace.