When unified logging was introduced we aliased numerous Print/TraceXXX flags to turn on their UL counterpart. For example:

-XX:+PrintSharedSpaces is deprecated. Will use -Xlog:cds=info instead.

UL has been around long enough now that we can obsolete and then expire these aliases. The affected flags are:

  { "PrintSharedSpaces",         LogLevel::Info,  true,  LOG_TAGS(cds) },
  { "TraceBiasedLocking",        LogLevel::Info,  true,  LOG_TAGS(biasedlocking) },
  { "TraceClassLoading",         LogLevel::Info,  true,  LOG_TAGS(class, load) },
  { "TraceClassLoadingPreorder", LogLevel::Debug, true,  LOG_TAGS(class, preorder) },
  { "TraceClassPaths",           LogLevel::Info,  true,  LOG_TAGS(class, path) },
  { "TraceClassResolution",      LogLevel::Debug, true,  LOG_TAGS(class, resolve) },
  { "TraceClassUnloading",       LogLevel::Info,  true,  LOG_TAGS(class, unload) },
  { "TraceExceptions",           LogLevel::Info,  true,  LOG_TAGS(exceptions) },
  { "TraceInvokeDynamic",        LogLevel::Debug, true,  LOG_TAGS(methodhandles, indy) },
  { "TraceLoaderConstraints",    LogLevel::Info,  true,  LOG_TAGS(class, loader, constraints) },
  { "TraceMethodHandles",        LogLevel::Info,  true,  LOG_TAGS(methodhandles) },
  { "TraceMonitorInflation",     LogLevel::Trace, true,  LOG_TAGS(monitorinflation) },
  { "TraceSafepointCleanupTime", LogLevel::Info,  true,  LOG_TAGS(safepoint, cleanup) },
  { "TraceJVMTIObjectTagging",   LogLevel::Debug, true,  LOG_TAGS(jvmti, objecttagging) },
  { "TraceRedefineClasses",      LogLevel::Info,  false, LOG_TAGS(redefine, class) },
  { "PrintJNIResolving",         LogLevel::Debug, true,  LOG_TAGS(jni, resolve) },

As noted in the source:

// NOTE: A compatibility request will be necessary for each alias to be removed.

We can continue to print what the equivalent -Xlog configuration is, but in-line with these flags being obsolete we will not set that Xlog configuration. (obsolete flags are ignored other than to produce a usage warning.)