code: public static Sampler create(final float rate) {
          if (rate == 0) {
              return NEVER_SAMPLE;
          }
          if (rate == 1.0) {
              return ALWAYS_SAMPLE;
          }
          if (rate < 0.01f || rate > 1) {
              throw new IllegalArgumentException("rate should be between 0.01 and 1: was " + rate);
          }
          return new CountingSampler(rate);
      }
docs: Creates a new instance.
  
  @param rate 0 means never sample, 1 means always sample. Otherwise minimum sample rate is 0.01,
  or 1% of traces