diff --git a/.github/workflows/sonarcloud-analysis.yml b/.github/workflows/sonarcloud-analysis.yml
index dd85e358..2ed0c3a2 100644
--- a/.github/workflows/sonarcloud-analysis.yml
+++ b/.github/workflows/sonarcloud-analysis.yml
@@ -9,14 +9,14 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
         with:
           fetch-depth: 0  # Shallow clones should be disabled for a better relevancy of analysis
-      - name: Set up JDK 11
+      - name: Set up JDK 17
         uses: actions/setup-java@v3
         with:
           distribution: zulu
-          java-version: 11
+          java-version: 17
       - name: Cache SonarCloud packages
         uses: actions/cache@v3
         with:
@@ -28,7 +28,7 @@ jobs:
         with:
           path: ~/.m2
           key: ${{ runner.os }}-m2-v11-${{ hashFiles('**/pom.xml') }}
-          restore-keys: ${{ runner.os }}-m2-v11
+          restore-keys: ${{ runner.os }}-m2-v17
       - name: Build and analyze
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}  # Needed to get PR information, if any
diff --git a/pom.xml b/pom.xml
index 66549ade..a7403636 100644
--- a/pom.xml
+++ b/pom.xml
@@ -22,7 +22,7 @@
         <maven-surefire-plugin.version>2.22.2</maven-surefire-plugin.version>
         <maven-source-plugin.version>3.3.0</maven-source-plugin.version>
         <maven-javadoc-plugin.version>3.6.2</maven-javadoc-plugin.version>
-        <jacoco.version>0.8.5</jacoco.version>
+        <jacoco.version>0.8.8</jacoco.version>
         <sonar.coverage.jacoco.xmlReportPaths>
             ${project.basedir}/../jacoco-coverage-report/target/site/jacoco-aggregate/jacoco.xml
         </sonar.coverage.jacoco.xmlReportPaths>
@@ -113,7 +113,7 @@
                     </execution>
                 </executions>
             </plugin>
-            <!-- Build Javacdoc JAR during packaging -->
+            <!-- Build Javadoc JAR during packaging -->
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-javadoc-plugin</artifactId>
@@ -152,7 +152,7 @@
 
     <!-- For publishing the library to GitHub Packages/GitLab Package Repository -->
     <distributionManagement>
-        <!-- Github Packages does not currently support public access, so disabled until it does.
+        <!-- GitHub Packages does not currently support public access, so disabled until it does.
              See https://github.community/t/download-from-github-package-registry-without-authentication/14407
         <repository>
             <id>github</id>
diff --git a/src/main/java/eu/webeid/security/util/DateAndTime.java b/src/main/java/eu/webeid/security/util/DateAndTime.java
index 0e5b0092..35e4f266 100644
--- a/src/main/java/eu/webeid/security/util/DateAndTime.java
+++ b/src/main/java/eu/webeid/security/util/DateAndTime.java
@@ -45,7 +45,12 @@ public static void requirePositiveDuration(Duration duration, String fieldName)
 
     public static class DefaultClock implements Clock {
 
-        public static final Clock INSTANCE = new DefaultClock();
+        // Allows mocking of time-dependent behavior with Mockito.mockStatic().
+        private static final Clock instance = new DefaultClock();
+
+        public static Clock getInstance() {
+            return instance;
+        }
 
         @Override
         public Date now() {
diff --git a/src/main/java/eu/webeid/security/validator/certvalidators/SubjectCertificateExpiryValidator.java b/src/main/java/eu/webeid/security/validator/certvalidators/SubjectCertificateExpiryValidator.java
index 90e35076..e24119d2 100644
--- a/src/main/java/eu/webeid/security/validator/certvalidators/SubjectCertificateExpiryValidator.java
+++ b/src/main/java/eu/webeid/security/validator/certvalidators/SubjectCertificateExpiryValidator.java
@@ -52,7 +52,7 @@ public SubjectCertificateExpiryValidator(Set<TrustAnchor> trustedCACertificateAn
      */
     public void validateCertificateExpiry(X509Certificate subjectCertificate) throws AuthTokenException {
         // Use the clock instance so that the date can be mocked in tests.
-        final Date now = DateAndTime.DefaultClock.INSTANCE.now();
+        final Date now = DateAndTime.DefaultClock.getInstance().now();
         CertificateValidator.trustedCACertificatesAreValidOnDate(trustedCACertificateAnchors, now);
         LOG.debug("CA certificates are valid.");
         CertificateValidator.certificateIsValidOnDate(subjectCertificate, now, "User");
diff --git a/src/main/java/eu/webeid/security/validator/certvalidators/SubjectCertificateTrustedValidator.java b/src/main/java/eu/webeid/security/validator/certvalidators/SubjectCertificateTrustedValidator.java
index 0471d5a6..91f4c194 100644
--- a/src/main/java/eu/webeid/security/validator/certvalidators/SubjectCertificateTrustedValidator.java
+++ b/src/main/java/eu/webeid/security/validator/certvalidators/SubjectCertificateTrustedValidator.java
@@ -56,7 +56,7 @@ public SubjectCertificateTrustedValidator(Set<TrustAnchor> trustedCACertificateA
      */
     public void validateCertificateTrusted(X509Certificate subjectCertificate) throws AuthTokenException {
         // Use the clock instance so that the date can be mocked in tests.
-        final Date now = DateAndTime.DefaultClock.INSTANCE.now();
+        final Date now = DateAndTime.DefaultClock.getInstance().now();
         subjectCertificateIssuerCertificate = CertificateValidator.validateIsSignedByTrustedCA(
             subjectCertificate,
             trustedCACertificateAnchors,
diff --git a/src/test/java/eu/webeid/security/testutil/Dates.java b/src/test/java/eu/webeid/security/testutil/Dates.java
index d6179c1c..fb5531bb 100644
--- a/src/test/java/eu/webeid/security/testutil/Dates.java
+++ b/src/test/java/eu/webeid/security/testutil/Dates.java
@@ -23,42 +23,19 @@
 package eu.webeid.security.testutil;
 
 import com.fasterxml.jackson.databind.util.StdDateFormat;
-import io.jsonwebtoken.Clock;
-import eu.webeid.security.util.DateAndTime;
 
-import java.lang.reflect.Field;
-import java.lang.reflect.Modifier;
 import java.text.ParseException;
 import java.util.Date;
 
 public final class Dates {
     private static final StdDateFormat STD_DATE_FORMAT = new StdDateFormat();
 
-    public static Date create(String iso8601Date) throws ParseException {
-        return STD_DATE_FORMAT.parse(iso8601Date);
-    }
-
-    public static void setMockedCertificateValidatorDate(Date mockedDate) throws NoSuchFieldException, IllegalAccessException {
-        setClockField(DateAndTime.DefaultClock.class, mockedDate);
-    }
-
-    public static void resetMockedCertificateValidatorDate() throws NoSuchFieldException, IllegalAccessException {
-        setClockField(DateAndTime.DefaultClock.class, new Date());
-    }
-
-    private static void setClockField(Class<? extends Clock> cls, Date date) throws NoSuchFieldException, IllegalAccessException {
-        final Field clockField = cls.getDeclaredField("INSTANCE");
-        setFinalStaticField(clockField, (Clock) () -> date);
-    }
-
-    private static void setFinalStaticField(Field field, Object newValue) throws NoSuchFieldException, IllegalAccessException {
-        field.setAccessible(true);
-
-        final Field modifiersField = Field.class.getDeclaredField("modifiers");
-        modifiersField.setAccessible(true);
-        modifiersField.setInt(field, field.getModifiers() & ~Modifier.FINAL);
-
-        field.set(null, newValue);
+    public static Date create(String iso8601Date) {
+        try {
+            return STD_DATE_FORMAT.parse(iso8601Date);
+        } catch (ParseException e) {
+            throw new RuntimeException(e);
+        }
     }
 
 }
diff --git a/src/test/java/eu/webeid/security/validator/AuthTokenCertificateTest.java b/src/test/java/eu/webeid/security/validator/AuthTokenCertificateTest.java
index 2234c235..ee090083 100644
--- a/src/test/java/eu/webeid/security/validator/AuthTokenCertificateTest.java
+++ b/src/test/java/eu/webeid/security/validator/AuthTokenCertificateTest.java
@@ -24,19 +24,32 @@
 
 import com.fasterxml.jackson.databind.exc.MismatchedInputException;
 import eu.webeid.security.authtoken.WebEidAuthToken;
-import eu.webeid.security.exceptions.*;
+import eu.webeid.security.exceptions.AuthTokenException;
+import eu.webeid.security.exceptions.AuthTokenParseException;
+import eu.webeid.security.exceptions.CertificateDecodingException;
+import eu.webeid.security.exceptions.CertificateExpiredException;
+import eu.webeid.security.exceptions.CertificateNotTrustedException;
+import eu.webeid.security.exceptions.CertificateNotYetValidException;
+import eu.webeid.security.exceptions.UserCertificateDisallowedPolicyException;
+import eu.webeid.security.exceptions.UserCertificateMissingPurposeException;
+import eu.webeid.security.exceptions.UserCertificateRevokedException;
+import eu.webeid.security.exceptions.UserCertificateWrongPurposeException;
 import eu.webeid.security.testutil.AbstractTestWithValidator;
 import eu.webeid.security.testutil.AuthTokenValidators;
 import eu.webeid.security.testutil.Dates;
+import eu.webeid.security.util.DateAndTime;
+import io.jsonwebtoken.Clock;
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Disabled;
 import org.junit.jupiter.api.Test;
+import org.mockito.MockedStatic;
 
 import java.security.cert.CertificateException;
-import java.text.ParseException;
+import java.util.Date;
 
 import static org.assertj.core.api.Assertions.assertThatThrownBy;
+import static org.mockito.Mockito.mockStatic;
 
 class AuthTokenCertificateTest extends AbstractTestWithValidator {
 
@@ -56,21 +69,20 @@ class AuthTokenCertificateTest extends AbstractTestWithValidator {
     private static final String EXPIRED_ECDSA_CERT = "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";
     private static final String REVOKED_CERT = "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";
 
+    private MockedStatic<DateAndTime.DefaultClock> mockedClock;
+
     @Override
     @BeforeEach
     protected void setup() {
         super.setup();
+        mockedClock = mockStatic(DateAndTime.DefaultClock.class);
         // Ensure that the certificates do not expire.
         mockDate("2021-08-01");
     }
 
     @AfterEach
     public void tearDown() {
-        try {
-            Dates.resetMockedCertificateValidatorDate();
-        } catch (NoSuchFieldException | IllegalAccessException e) {
-            throw new RuntimeException(e);
-        }
+        mockedClock.close();
     }
 
     @Test
@@ -275,11 +287,8 @@ void whenCertificateCaIsNotPartOfTrustChain_thenValidationFails() throws Excepti
     }
 
     private void mockDate(String date) {
-        try {
-            Dates.setMockedCertificateValidatorDate(Dates.create(date));
-        } catch (ParseException | NoSuchFieldException | IllegalAccessException e) {
-            throw new RuntimeException(e);
-        }
+        final Date theDate = Dates.create(date);
+        mockedClock.when(DateAndTime.DefaultClock::getInstance).thenReturn((Clock) () -> theDate);
     }
 
 }
diff --git a/src/test/java/eu/webeid/security/validator/certvalidators/SubjectCertificateNotRevokedValidatorTest.java b/src/test/java/eu/webeid/security/validator/certvalidators/SubjectCertificateNotRevokedValidatorTest.java
index b4df0496..faaea759 100644
--- a/src/test/java/eu/webeid/security/validator/certvalidators/SubjectCertificateNotRevokedValidatorTest.java
+++ b/src/test/java/eu/webeid/security/validator/certvalidators/SubjectCertificateNotRevokedValidatorTest.java
@@ -114,14 +114,14 @@ void whenOcspUrlIsInvalid_thenThrows() throws Exception {
 
     @Test
     void whenOcspRequestFails_thenThrows() throws Exception {
-        final OcspServiceProvider ocspServiceProvider = getDesignatedOcspServiceProvider("https://web-eid-test.free.beeceptor.com");
+        final OcspServiceProvider ocspServiceProvider = getDesignatedOcspServiceProvider("http://demo.sk.ee/ocsps");
         final SubjectCertificateNotRevokedValidator validator = new SubjectCertificateNotRevokedValidator(trustedValidator, ocspClient, ocspServiceProvider);
         assertThatCode(() ->
             validator.validateCertificateNotRevoked(estEid2018Cert))
             .isInstanceOf(UserCertificateOCSPCheckFailedException.class)
             .cause()
             .isInstanceOf(IOException.class)
-            .hasMessageStartingWith("OCSP request was not successful, response: (POST https://web-eid-test.free.beeceptor.com) 404");
+            .hasMessageStartingWith("OCSP request was not successful, response: (POST http://demo.sk.ee/ocsps) 404");
     }
 
     @Test