some minor util class clean-up, to prevent instanciation of util classes

core/src/main/java/org/keycloak/util/DerUtils.java

@@ -20,11 +20,14 @@ import java.security.spec.X509EncodedKeySpec;
  * @author <a href="mailto:bill@burkecentral.com">Bill Burke</a>
  * @version $Revision: 1 $
  */
-public class DerUtils {
+public final class DerUtils {
     static {
         BouncyIntegration.init();
     }
 
+    private DerUtils() {
+    }
+
     public static PrivateKey decodePrivateKey(InputStream is)
             throws Exception {
 

core/src/main/java/org/keycloak/util/EnvUtil.java

@@ -7,9 +7,13 @@ import java.util.regex.Pattern;
  * @author <a href="mailto:bill@burkecentral.com">Bill Burke</a>
  * @version $Revision: 1 $
  */
-public class EnvUtil {
+public final class EnvUtil {
     private static final Pattern p = Pattern.compile("[$][{]([^}]+)[}]");
 
+    private EnvUtil() {
+
+    }
+
     /**
      * Replaces any ${} strings with their corresponding environent variable.
      *

core/src/main/java/org/keycloak/util/PemUtils.java

@@ -15,11 +15,14 @@ import java.security.cert.X509Certificate;
  * @author <a href="mailto:bill@burkecentral.com">Bill Burke</a>
  * @version $Revision: 1 $
  */
-public class PemUtils {
+public final class PemUtils {
     static {
         BouncyIntegration.init();
     }
 
+    private PemUtils() {
+    }
+
     public static X509Certificate decodeCertificate(InputStream is) throws Exception {
         byte[] der = pemToDer(is);
         ByteArrayInputStream bis = new ByteArrayInputStream(der);

core/src/main/java/org/keycloak/util/StreamUtil.java

@@ -9,7 +9,11 @@ import java.io.InputStreamReader;
  * @author <a href="mailto:bill@burkecentral.com">Bill Burke</a>
  * @version $Revision: 1 $
  */
-public class StreamUtil {
+public final class StreamUtil {
+
+    private StreamUtil() {
+    }
+
     public static String readString(InputStream in) throws IOException
     {
         char[] buffer = new char[1024];

model/api/src/main/java/org/keycloak/models/utils/KeycloakSessionUtils.java

@@ -5,7 +5,10 @@ import java.util.concurrent.atomic.AtomicLong;
 /**
  * @author <a href="mailto:mposolda@redhat.com">Marek Posolda</a>
  */
-public class KeycloakSessionUtils {
+public final class KeycloakSessionUtils {
+
+    private KeycloakSessionUtils() {
+    }
 
     private static AtomicLong counter = new AtomicLong(1);
 

testsuite/performance/src/test/java/org/keycloak/testsuite/performance/PerfTestUtils.java

@@ -3,7 +3,10 @@ package org.keycloak.testsuite.performance;
 /**
  * @author <a href="mailto:mposolda@redhat.com">Marek Posolda</a>
  */
-public class PerfTestUtils {
+public final class PerfTestUtils {
+
+    private PerfTestUtils() {
+    }
 
     public static <T> T readSystemProperty(String propertyName, Class<T> expectedClass) {
         String propAsString = System.getProperty(propertyName);