public long pendingAcquisitionDurationNanos() {
        return pendingAcquisitionDurationNanos;
    }
Returns the duration which was taken to wait for the completion of an existing connection attempt
in order to use one connection for HTTP/2.

@return the duration, or {@code -1} if there was no action to get a pending connection.
core/src/main/java/com/linecorp/armeria/common/logging/ClientConnectionTimings.java