Fix exception comments and add imports

Author: KostasTsiounis

closed/src/java.base/share/classes/openj9/internal/security/RestrictedSecurity.java

@@ -857,7 +857,8 @@ boolean isRestrictedServiceAllowed(Service service, boolean isServiceAdded) {
                 if (!isServiceAdded && !isNullOrBlank(cAcceptedUses)) {
                     String[] optionAndValue = cAcceptedUses.split(":");
                     if (optionAndValue.length != 2) {
-                        printStackTraceAndExit("Incorrect specification of accepted uses in constraint: " + constraint);
+                        printStackTraceAndExit("Incorrect specification of accepted uses in constraint: '"
+                            + constraint + "'. Couldn't find option and value separated by ':'");
                     }
                     String option = optionAndValue[0];
                     String value = optionAndValue[1];
@@ -879,7 +880,8 @@ boolean isRestrictedServiceAllowed(Service service, boolean isServiceAdded) {
                             case "ModuleAndFullClassName":
                                 String[] moduleAndFullClassName = value.split("/");
                                 if (moduleAndFullClassName.length != 2) {
-                                    printStackTraceAndExit("Incorrect specification of accepted uses in constraint: " + constraint);
+                                    printStackTraceAndExit("Incorrect specification of accepted uses in constraint: '"
+                                        + constraint + "'. Couldn't find module and classname separated by '/'");
                                 }
                                 module = moduleAndFullClassName[0];
                                 String fullClassName = moduleAndFullClassName[1];
@@ -889,7 +891,8 @@ boolean isRestrictedServiceAllowed(Service service, boolean isServiceAdded) {
                             case "ModuleAndPackage":
                                 String[] moduleAndPackage = value.split("/");
                                 if (moduleAndPackage.length != 2) {
-                                    printStackTraceAndExit("Incorrect specification of accepted uses in constraint: " + constraint);
+                                    printStackTraceAndExit("Incorrect specification of accepted uses in constraint: '"
+                                        + constraint + "'. Couldn't find module and classname separated by '/'");
                                 }
                                 module = moduleAndPackage[0];
                                 String packageValue = moduleAndPackage[1];

closed/test/jdk/openj9/internal/security/TestConstraintsFailure.java

@@ -28,6 +28,7 @@
  * @library /test/lib
  * @run junit TestConstraintsFailure
  */
+import org.junit.jupiter.api.Test;
 
 import java.security.AlgorithmParameterGenerator;
 import java.security.KeyFactory;

closed/test/jdk/openj9/internal/security/TestConstraintsSuccess.java

@@ -28,6 +28,7 @@
  * @library /test/lib
  * @run junit TestConstraintsSuccess
  */
+import org.junit.jupiter.api.Test;
 
 import java.security.AlgorithmParameterGenerator;
 import java.security.KeyFactory;