Compiler warning in ctrl_dhcp6_srv_unittest.cc test on Centos 7.5

Getting a compiler warning on Centos 7.5/gcc (GCC) 4.8.5 20150623 (Red Hat 4.8.5-28)

git.tip/kea/install-sh\" -DCFG_EXAMPLES=\"/home/tmark/labs/build/keadev/sandbox/git.tip/kea/doc/examples/kea6\" -I/opt/googletest-release-1.8.0/googletest -I/opt/googletest-release-1.8.0/googletest/include -DOS_LINUX  -Wall -Wextra -Wnon-virtual-dtor -Wwrite-strings -Woverloaded-virtual -Wno-sign-compare -pthread -Wno-missing-field-initializers -fPIC -g -O2 -fmax-errors=4 -MT dhcp6_unittests-decline_unittest.o -MD -MP -MF .deps/dhcp6_unittests-decline_unittest.Tpo -c -o dhcp6_unittests-decline_unittest.o `test -f 'decline_unittest.cc' || echo './'`decline_unittest.cc
In file included from /opt/googletest-release-1.8.0/googletest/include/gtest/gtest.h:1874:0,
                 from ../../../../src/bin/dhcp6/tests/dhcp6_test_utils.h:14,
                 from ctrl_dhcp6_srv_unittest.cc:17:
ctrl_dhcp6_srv_unittest.cc: In member function ‘virtual void {anonymous}::CtrlChannelDhcpv6SrvTest_statusGet_Test::TestBody()’:
/opt/googletest-release-1.8.0/googletest/include/gtest/internal/gtest-internal.h:133:55: warning: converting ‘false’ to pointer type for argument 1 of ‘char testing::internal::IsNullLiteralHelper(testing::internal::Secret*)’ [-Wconversion-null]
     (sizeof(::testing::internal::IsNullLiteralHelper(x)) == 1)
                                                       ^
/opt/googletest-release-1.8.0/googletest/include/gtest/gtest_pred_impl.h:77:52: note: in definition of macro ‘GTEST_ASSERT_’
   if (const ::testing::AssertionResult gtest_ar = (expression)) \
                                                    ^
/opt/googletest-release-1.8.0/googletest/include/gtest/gtest_pred_impl.h:162:3: note: in expansion of macro ‘GTEST_PRED_FORMAT2_’
   GTEST_PRED_FORMAT2_(pred_format, v1, v2, GTEST_NONFATAL_FAILURE_)
   ^
/opt/googletest-release-1.8.0/googletest/include/gtest/gtest.h:1923:3: note: in expansion of macro ‘EXPECT_PRED_FORMAT2’
   EXPECT_PRED_FORMAT2(::testing::internal:: \
   ^
/opt/googletest-release-1.8.0/googletest/include/gtest/gtest.h:1924:32: note: in expansion of macro ‘GTEST_IS_NULL_LITERAL_’
                       EqHelper<GTEST_IS_NULL_LITERAL_(val1)>::Compare, \
                                ^
ctrl_dhcp6_srv_unittest.cc:1015:5: note: in expansion of macro ‘EXPECT_EQ’
     EXPECT_EQ(false, found_multi_threading->boolValue());
     ^

Same thing for src/dhcp4