Linux x86_64, minimal, slowdebug:

Creating symlink jdk/lib/security/public_suffix_list.dat
/home/buildbot/worker/jdk11u/build/build/linux-x86_64-normal-minimal-slowdebug/hotspot/variant-minimal/libjvm/objs/memAllocator.o: In function `MemAllocator::Allocation::notify_allocation_jvmti_sampler()':
/home/buildbot/worker/jdk11u/build/src/hotspot/share/gc/shared/memAllocator.cpp:210: undefined reference to `JvmtiSampledObjectAllocEventCollector::object_alloc_is_safe_to_sample()'
collect2: error: ld returned 1 exit status
lib/CompileJvm.gmk:149: recipe for target '/home/buildbot/worker/jdk11u/build/build/linux-x86_64-normal-minimal-slowdebug/support/modules_libs/java.base/minimal/libjvm.so' failed
make[3]: *** [/home/buildbot/worker/jdk11u/build/build/linux-x86_64-normal-minimal-slowdebug/support/modules_libs/java.base/minimal/libjvm.so] Error 1

It manifests only in jdk-updates/jdk11u, only in minimal, and only in slowdebug, which is why it was never found?

The usage in jdk11u is:

void MemAllocator::Allocation::notify_allocation_jvmti_sampler() {
  ...
  // Only check if the sampler could actually sample something in this path.
  assert(!JvmtiExport::should_post_sampled_object_alloc() ||
         !JvmtiSampledObjectAllocEventCollector::object_alloc_is_safe_to_sample() ||
         _thread->heap_sampler().sampling_collector_present(),
         "Sampling collector not present.");