public DelegationChecker<D, W, T> defineMockConfigurationForVoidMethodInvocation(Consumer<D> mockConsumer) {
        this.mockConsumer = Objects.requireNonNull(mockConsumer);
        return this;
    }
@param wrapper the wrapper
@return the underlying delegate for the given wrapper
server-common/src/test/java/org/apache/kafka/server/immutable/DelegationChecker.java