public AbstractLoggingClientBuilder samplingRate(float samplingRate) {
        checkArgument(0.0 <= samplingRate && samplingRate <= 1.0,
                      "samplingRate: %s (expected: 0.0 <= samplingRate <= 1.0)", samplingRate);
        return sampler(Sampler.random(samplingRate));
    }
Sets the rate at which to sample requests to log. Any number between {@code 0.0} and {@code 1.0} will
cause a random sample of the requests to be logged.
This method sets both success and failure sampling rate.
Use {@link #successSamplingRate(float)} and {@link #failureSamplingRate(float)}
if you want to specify a different sampling rate for each case.
core/src/main/java/com/linecorp/armeria/client/logging/AbstractLoggingClientBuilder.java