private Meter.Id actualId() {
    return actual.getId();
  }
Verifies that the meter has the given base unit.

@param expectedBaseUnit the expected base unit
@return this assertion object
@throws AssertionError if the meter is {@code null}
@throws AssertionError if the meter does not have the given base unit
geode-junit/src/main/java/org/apache/geode/test/micrometer/AbstractMeterAssert.java