@RequiresReadLock
  @RequiresBackgroundThread
  default @Nullable DocumentationTarget documentationTarget(@NotNull Project project, @NotNull Symbol symbol) {
    throw new IllegalStateException("Override this or documentationTargets(Project, Symbol)");
  }
@RequiresReadLock
  @RequiresBackgroundThread
  default @Nullable DocumentationTarget documentationTarget(@NotNull Project project, @NotNull Symbol symbol)