Differentiate warning by Java version

Author: ppkarwasz

log4j-api/src/main/java/org/apache/logging/log4j/util/StackLocator.java

@@ -72,11 +72,19 @@ public final class StackLocator {
             } else {
                 o = getCallerClassMethod.invoke(null, 1);
                 if (o == sunReflectionClass) {
-                    System.out.println("WARNING: Unexpected result from sun.reflect.Reflection.getCallerClass(int), adjusting offset for future calls.");
+                    LowLevelLogUtil.log(
+                            "WARNING: Unexpected result from sun.reflect.Reflection.getCallerClass(int), adjusting offset for future calls.");
                     java7u25CompensationOffset = 1;
                 }
             }
         } catch (final Exception | LinkageError e) {
+            if (Constants.JAVA_MAJOR_VERSION > 8) {
+                LowLevelLogUtil.log(
+                        "WARNING: Runtime environment does not support multi-release JARs. This will impact location-based features.");
+            } else {
+                LowLevelLogUtil.log(
+                        "WARNING: sun.reflect.Reflection.getCallerClass is not supported. This will impact location-based features.");
+            }
             getCallerClassMethod = null;
             java7u25CompensationOffset = -1;
         }