@Override
    public String toString() {
        // 33 + 31 + 26 + 23 + 26 + 23 + 31 + 28 + 45 * 4 + 16 * 4 + 1 = 466
        final StringBuilder buf = new StringBuilder(TO_STRING_BUILDER_CAPACITY);
        buf.append("{connectionAcquisitionStartTime=");
        TextFormatter.appendEpochMicros(buf, connectionAcquisitionStartTimeMicros);
        buf.append(", connectionAcquisitionDuration=");
        TextFormatter.appendElapsed(buf, connectionAcquisitionDurationNanos);

        if (dnsResolutionDurationNanos >= 0) {
            buf.append(", dnsResolutionStartTime=");
            TextFormatter.appendEpochMicros(buf, dnsResolutionStartTimeMicros);
            buf.append(", dnsResolutionDuration=");
            TextFormatter.appendElapsed(buf, dnsResolutionDurationNanos);
        }

        if (socketConnectDurationNanos >= 0) {
            buf.append(", socketConnectStartTime=");
            TextFormatter.appendEpochMicros(buf, socketConnectStartTimeMicros);
            buf.append(", socketConnectDuration=");
            TextFormatter.appendElapsed(buf, socketConnectDurationNanos);
        }

        if (tlsHandshakeDurationNanos >= 0) {
            buf.append(", tlsHandshakeStartTime=");
            TextFormatter.appendEpochMicros(buf, tlsHandshakeStartTimeMicros);
            buf.append(", tlsHandshakeDuration=");
            TextFormatter.appendElapsed(buf, tlsHandshakeDurationNanos);
        }

        if (pendingAcquisitionDurationNanos >= 0) {
            buf.append(", pendingAcquisitionStartTime=");
            TextFormatter.appendEpochMicros(buf, pendingAcquisitionStartTimeMicros);
            buf.append(", pendingAcquisitionDuration=");
            TextFormatter.appendElapsed(buf, pendingAcquisitionDurationNanos);
        }
        buf.append('}');
        return buf.toString();
    }
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