Fix #404: Utility classes should not have public constructors

enrollment-server-onboarding/src/main/java/com/wultra/app/onboardingserver/impl/util/DateUtil.java

@@ -27,7 +27,11 @@
  *
  * @author Roman Strobl, roman.strobl@wultra.com
  */
-public class DateUtil {
+public final class DateUtil {
+
+    private DateUtil() {
+        throw new IllegalStateException("Utility class");
+    }
 
     /**
      * Convert expiration time interval to minimal created date used for expiration.

enrollment-server-onboarding/src/main/java/com/wultra/app/onboardingserver/impl/util/PowerAuthUtil.java

@@ -22,11 +22,15 @@
 import io.getlime.security.powerauth.rest.api.spring.authentication.PowerAuthApiAuthentication;
 
 /**
- * PowerAuth utilities
+ * PowerAuth utilities.
  *
  * @author Lukas Lukovsky, lukas.lukovsky@wultra.com
  */
-public class PowerAuthUtil {
+public final class PowerAuthUtil {
+
+    private PowerAuthUtil() {
+        throw new IllegalStateException("Utility class");
+    }
 
     /**
      * Provides context data

enrollment-server-onboarding/src/main/java/com/wultra/app/onboardingserver/statemachine/util/StateContextUtil.java

@@ -27,11 +27,15 @@
 import java.util.Map;
 
 /**
- * State context util
+ * State context util.
  *
  * @author Lukas Lukovsky, lukas.lukovsky@wultra.com
  */
-public class StateContextUtil {
+public final class StateContextUtil {
+
+    private StateContextUtil() {
+        throw new IllegalStateException("Utility class");
+    }
 
     public static void setResponseOk(final StateContext<OnboardingState, OnboardingEvent> context, final Response response) {
         Preconditions.checkArgument(

enrollment-server-onboarding/src/test/java/com/wultra/app/test/TestUtil.java

@@ -24,11 +24,15 @@
 import java.io.InputStream;
 
 /**
- * Test utilities
+ * Test utilities.
  *
  * @author Lukas Lukovsky, lukas.lukovsky@wultra.com
  */
-public class TestUtil {
+public final class TestUtil {
+
+    private TestUtil() {
+        throw new IllegalStateException("Utility class");
+    }
 
     /**
      * Loads photo from a file