public DelegationChecker<D, W, T> defineMockConfigurationForUnsupportedFunction(Function<D, T> mockConfigurationFunction) {
        this.mockConfigurationFunction = Objects.requireNonNull(mockConfigurationFunction);
        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