The issue is that no matter what I try, I keep in the JDK 17 environment the error: "NoSuchMethodException: sun.misc.Unsafe.defineClass(...) "

Environment is Mockito 2.x, 3.x, 4.2.0 (core). JDK17, Spring Boot 2.5.5.
Either in JUnit 4 or JUnit 5 environment.

The exact error:

org.mockito.exceptions.base.MockitoException:
Mockito cannot mock this class: class nl.*****.fortesting.ForTestingChild.

Mockito can only mock non-private & non-final classes.
If you're not sure why you're getting this error, please report to the mailing list.

The simplified classes are shown below.

What I tried so far is:

1. Any version of Mockito-core, e.g. 4.2.0.

2. Remove Mockito core from the spring-boot-test-starter.

3. Adding net.buddy explicitly

   net.bytebuddy byte-buddy 1.12.3 test net.bytebuddy byte-buddy-agent 1.12.3 test

4. Using mock( ) or @mock.

5. Working with a @MockBean or @mock.

6. With JUnit 4 or JUnit 5.

The simplified sample code:

@service
public class ForTestingChild {
public String getExternalStuff( String input) {
return "Get that external input";
}
}
The is the simplified class using the previous class:

@service
public class ForTestingThisIsParent {
private ForTestingChild forTestingChild;
public ForTestingThisIsParent( ForTestingChild forTestingChild) {
this.forTestingChild = forTestingChild;
}
public String getValueFromChild( String input) {
return forTestingChild.getExternalStuff( input);
}
}
This is the test class:

@RunWith(MockitoJUnitRunner.class)
public class ForTestingThisIsParentTest {
@mock
ForTestingChild forTestingChild;

@InjectMocks
ForTestingThisIsParent forTestingThisIsParent;

@Test
public void testBasic() {
    when( forTestingChild.getExternalStuff( any())).thenReturn( "Simulated external stuff");
    assertEquals( "Simulated external stuff", forTestingThisIsParent.getValueFromChild( "Nonesense stuff"));
}

}

The stacktrace:

org.mockito.exceptions.base.MockitoException:
Mockito cannot mock this class: class nl.*****.fortesting.ForTestingChild.

Mockito can only mock non-private & non-final classes.
If you're not sure why you're getting this error, please report to the mailing list.

Java : 17
JVM vendor name : Oracle Corporation
....

Underlying exception : java.lang.UnsupportedOperationException: Cannot define class using reflection

at org.mockito.internal.runners.DefaultInternalRunner$1.withBefores(DefaultInternalRunner.java:39)
at org.junit.runners.BlockJUnit4ClassRunner.methodBlock(BlockJUnit4ClassRunner.java:276)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
at org.mockito.internal.runners.DefaultInternalRunner$1.run(DefaultInternalRunner.java:79)
at org.mockito.internal.runners.DefaultInternalRunner.run(DefaultInternalRunner.java:85)
at org.mockito.internal.runners.StrictRunner.run(StrictRunner.java:39)
at org.mockito.junit.MockitoJUnitRunner.run(MockitoJUnitRunner.java:163)
at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:69)
at com.intellij.rt.junit.IdeaTestRunner$Repeater$1.execute(IdeaTestRunner.java:38)
at com.intellij.rt.execution.junit.TestsRepeater.repeat(TestsRepeater.java:11)
at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:35)
at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:235)
at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:54)

Caused by: java.lang.UnsupportedOperationException: Cannot define class using reflection
at net.bytebuddy.dynamic.loading.ClassInjector$UsingReflection$Dispatcher$Unavailable.defineClass(ClassInjector.java:821)
at net.bytebuddy.dynamic.loading.ClassInjector$UsingReflection.inject(ClassInjector.java:185)
at net.bytebuddy.dynamic.loading.ClassLoadingStrategy$Default$InjectionDispatcher.load(ClassLoadingStrategy.java:187)
at net.bytebuddy.dynamic.TypeResolutionStrategy$Passive.initialize(TypeResolutionStrategy.java:79)
at net.bytebuddy.dynamic.DynamicType$Default$Unloaded.load(DynamicType.java:4457)
at org.mockito.internal.creation.bytebuddy.SubclassBytecodeGenerator.mockClass(SubclassBytecodeGenerator.java:121)
at org.mockito.internal.creation.bytebuddy.TypeCachingBytecodeGenerator$1.call(TypeCachingBytecodeGenerator.java:37)
at org.mockito.internal.creation.bytebuddy.TypeCachingBytecodeGenerator$1.call(TypeCachingBytecodeGenerator.java:34)
at net.bytebuddy.TypeCache.findOrInsert(TypeCache.java:138)
at net.bytebuddy.TypeCache$WithInlineExpunction.findOrInsert(TypeCache.java:346)
at net.bytebuddy.TypeCache.findOrInsert(TypeCache.java:161)
at net.bytebuddy.TypeCache$WithInlineExpunction.findOrInsert(TypeCache.java:355)
at org.mockito.internal.creation.bytebuddy.TypeCachingBytecodeGenerator.mockClass(TypeCachingBytecodeGenerator.java:32)
at org.mockito.internal.creation.bytebuddy.SubclassByteBuddyMockMaker.createMockType(SubclassByteBuddyMockMaker.java:71)
at org.mockito.internal.creation.bytebuddy.SubclassByteBuddyMockMaker.createMock(SubclassByteBuddyMockMaker.java:42)
at org.mockito.internal.creation.bytebuddy.ByteBuddyMockMaker.createMock(ByteBuddyMockMaker.java:25)
at org.mockito.internal.util.MockUtil.createMock(MockUtil.java:35)
at org.mockito.internal.MockitoCore.mock(MockitoCore.java:65)
at org.mockito.Mockito.mock(Mockito.java:1855)
at org.mockito.internal.configuration.MockAnnotationProcessor.process(MockAnnotationProcessor.java:36)
at org.mockito.internal.configuration.MockAnnotationProcessor.process(MockAnnotationProcessor.java:16)
at org.mockito.internal.configuration.IndependentAnnotationEngine.createMockFor(IndependentAnnotationEngine.java:38)
at org.mockito.internal.configuration.IndependentAnnotationEngine.process(IndependentAnnotationEngine.java:62)
at org.mockito.internal.configuration.InjectingAnnotationEngine.processIndependentAnnotations(InjectingAnnotationEngine.java:57)
at org.mockito.internal.configuration.InjectingAnnotationEngine.process(InjectingAnnotationEngine.java:41)
at org.mockito.MockitoAnnotations.initMocks(MockitoAnnotations.java:69)
... 21 more
Caused by: java.lang.IllegalStateException: Could not find sun.misc.Unsafe
at net.bytebuddy.dynamic.loading.ClassInjector$UsingUnsafe$Dispatcher$Disabled.initialize(ClassInjector.java:1366)
at net.bytebuddy.dynamic.loading.ClassInjector$UsingUnsafe.inject(ClassInjector.java:1202)
at net.bytebuddy.dynamic.loading.ClassLoadingStrategy$ForUnsafeInjection.load(ClassLoadingStrategy.java:458)
at net.bytebuddy.dynamic.TypeResolutionStrategy$Passive.initialize(TypeResolutionStrategy.java:79)
at net.bytebuddy.dynamic.DynamicType$Default$Unloaded.load(DynamicType.java:4457)
at net.bytebuddy.dynamic.loading.ClassInjector$UsingReflection$Dispatcher$Indirect.make(ClassInjector.java:684)
at net.bytebuddy.dynamic.loading.ClassInjector$UsingReflection$Dispatcher$CreationAction.run(ClassInjector.java:302)
at net.bytebuddy.dynamic.loading.ClassInjector$UsingReflection$Dispatcher$CreationAction.run(ClassInjector.java:290)
at java.base/java.security.AccessController.doPrivileged(AccessController.java:318)
at net.bytebuddy.dynamic.loading.ClassInjector$UsingReflection.(ClassInjector.java:70)
at net.bytebuddy.dynamic.loading.ClassLoadingStrategy$Default$InjectionDispatcher.load(ClassLoadingStrategy.java:184)
... 44 more
Caused by: java.lang.NoSuchMethodException: sun.misc.Unsafe.defineClass(java.lang.String,[B,int,int,java.lang.ClassLoader,java.security.ProtectionDomain)
at java.base/java.lang.Class.getMethod(Class.java:2227)
at net.bytebuddy.dynamic.loading.ClassInjector$UsingUnsafe$Dispatcher$CreationAction.run(ClassInjector.java:1269)
at net.bytebuddy.dynamic.loading.ClassInjector$UsingUnsafe$Dispatcher$CreationAction.run(ClassInjector.java:1257)
at java.base/java.security.AccessController.doPrivileged(AccessController.java:318)
at net.bytebuddy.dynamic.loading.ClassInjector$UsingUnsafe.(ClassInjector.java:1136)

The package versions:

+- org.springframework.boot:spring-boot-starter:jar:2.5.5:compile
| +- org.springframework.boot:spring-boot:jar:2.5.5:compile
| | - org.springframework:spring-context:jar:5.3.10:compile
| +- org.springframework.boot:spring-boot-autoconfigure:jar:2.5.5:compile
| +- jakarta.annotation:jakarta.annotation-api:jar:1.3.5:compile
| +- org.springframework:spring-core:jar:5.3.10:compile
| | - org.springframework:spring-jcl:jar:5.3.10:compile
| - org.yaml:snakeyaml:jar:1.28:compile
+- org.springframework.boot:spring-boot-starter-log4j2:jar:2.5.5:compile
| +- org.apache.logging.log4j:log4j-slf4j-impl:jar:2.14.1:compile
| | - org.apache.logging.log4j:log4j-api:jar:2.14.1:compile
| +- org.apache.logging.log4j:log4j-core:jar:2.14.1:compile
| +- org.apache.logging.log4j:log4j-jul:jar:2.14.1:compile
| - org.slf4j:jul-to-slf4j:jar:1.7.32:compile
+- org.springframework.boot:spring-boot-starter-web:jar:2.5.5:compile
| +- org.springframework.boot:spring-boot-starter-json:jar:2.5.5:compile
| | +- com.fasterxml.jackson.datatype:jackson-datatype-jdk8:jar:2.12.5:compile
| | - com.fasterxml.jackson.module:jackson-module-parameter-names:jar:2.12.5:compile
| +- org.springframework.boot:spring-boot-starter-tomcat:jar:2.5.5:compile
| | +- org.apache.tomcat.embed:tomcat-embed-core:jar:9.0.53:compile
| | - org.apache.tomcat.embed:tomcat-embed-websocket:jar:9.0.53:compile
| +- org.springframework:spring-web:jar:5.3.10:compile
| | - org.springframework:spring-beans:jar:5.3.10:compile
| - org.springframework:spring-webmvc:jar:5.3.10:compile
| +- org.springframework:spring-aop:jar:5.3.10:compile
| - org.springframework:spring-expression:jar:5.3.10:compile
+- org.springframework.boot:spring-boot-starter-data-rest:jar:2.5.5:compile
| - org.springframework.data:spring-data-rest-webmvc:jar:3.5.5:compile
| - org.springframework.data:spring-data-rest-core:jar:3.5.5:compile
| +- org.springframework.hateoas:spring-hateoas:jar:1.3.4:compile
| +- org.springframework.plugin:spring-plugin-core:jar:2.0.0.RELEASE:compile
| - org.atteo:evo-inflector:jar:1.2.2:compile
+- org.springframework.boot:spring-boot-starter-data-jpa:jar:2.5.5:compile
| +- org.springframework.boot:spring-boot-starter-aop:jar:2.5.5:compile
| | - org.aspectj:aspectjweaver:jar:1.9.7:compile
| +- org.springframework.boot:spring-boot-starter-jdbc:jar:2.5.5:compile
| | +- com.zaxxer:HikariCP:jar:4.0.3:compile
| | - org.springframework:spring-jdbc:jar:5.3.10:compile
| +- jakarta.transaction:jakarta.transaction-api:jar:1.3.3:compile
| +- jakarta.persistence:jakarta.persistence-api:jar:2.2.3:compile
| +- org.hibernate:hibernate-core:jar:5.4.32.Final:compile
| | +- org.jboss.logging:jboss-logging:jar:3.4.2.Final:compile
| | +- org.javassist:javassist:jar:3.27.0-GA:compile
| | +- net.bytebuddy:byte-buddy:jar:1.10.22:compile
| | +- antlr:antlr:jar:2.7.7:compile
| | +- org.jboss:jandex:jar:2.2.3.Final:compile
| | +- com.fasterxml:classmate:jar:1.5.1:compile
| | +- org.dom4j:dom4j:jar:2.1.3:compile
| | +- org.hibernate.common:hibernate-commons-annotations:jar:5.1.2.Final:compile
| | - org.glassfish.jaxb:jaxb-runtime:jar:2.3.5:compile
| | +- org.glassfish.jaxb:txw2:jar:2.3.5:compile
| | +- com.sun.istack:istack-commons-runtime:jar:3.0.12:compile
| | - com.sun.activation:jakarta.activation:jar:1.2.2:runtime
| +- org.springframework.data:spring-data-jpa:jar:2.5.5:compile
| | +- org.springframework.data:spring-data-commons:jar:2.5.5:compile
| | +- org.springframework:spring-orm:jar:5.3.10:compile
| | - org.springframework:spring-tx:jar:5.3.10:compile
| - org.springframework:spring-aspects:jar:5.3.10:compile
+- org.springframework.boot:spring-boot-starter-validation:jar:2.5.5:compile
| +- org.apache.tomcat.embed:tomcat-embed-el:jar:9.0.53:compile
| - org.hibernate.validator:hibernate-validator:jar:6.2.0.Final:compile
| - jakarta.validation:jakarta.validation-api:jar:2.0.2:compile
+- com.fasterxml.jackson.datatype:jackson-datatype-jsr310:jar:2.12.5:compile
| +- com.fasterxml.jackson.core:jackson-annotations:jar:2.12.5:compile
| +- com.fasterxml.jackson.core:jackson-core:jar:2.12.5:compile
| - com.fasterxml.jackson.core:jackson-databind:jar:2.12.5:compile
+- mysql:mysql-connector-java:jar:8.0.25:compile
+- io.jsonwebtoken:jjwt:jar:0.9.1:compile
+- com.jayway.jsonpath:json-path:jar:2.6.0:compile
| +- net.minidev:json-smart:jar:2.4.7:compile
| | - net.minidev:accessors-smart:jar:2.4.7:compile
| - org.slf4j:slf4j-api:jar:1.7.32:compile
+- org.apache.httpcomponents:httpclient:jar:4.5.13:compile
| - org.apache.httpcomponents:httpcore:jar:4.4.14:compile
+- commons-codec:commons-codec:jar:1.15:compile
+- org.springframework.security:spring-security-crypto:jar:5.5.2:compile
+- com.squareup.okhttp3:okhttp:jar:4.9.3:compile
| +- com.squareup.okio:okio:jar:2.8.0:compile
| | - org.jetbrains.kotlin:kotlin-stdlib-common:jar:1.5.31:compile
| - org.jetbrains.kotlin:kotlin-stdlib:jar:1.5.31:compile
| - org.jetbrains:annotations:jar:13.0:compile
+- com.squareup.okhttp3:okhttp-urlconnection:jar:4.9.3:compile
| - org.jetbrains.kotlin:kotlin-stdlib-jdk8:jar:1.5.31:compile
| - org.jetbrains.kotlin:kotlin-stdlib-jdk7:jar:1.5.31:compile
+- org.springframework.boot:spring-boot-starter-test:jar:2.5.5:test
| +- org.springframework.boot:spring-boot-test:jar:2.5.5:test
| +- org.springframework.boot:spring-boot-test-autoconfigure:jar:2.5.5:test
| +- jakarta.xml.bind:jakarta.xml.bind-api:jar:2.3.3:compile
| | - jakarta.activation:jakarta.activation-api:jar:1.2.2:compile
| +- org.assertj:assertj-core:jar:3.19.0:test
| +- org.hamcrest:hamcrest:jar:2.2:test
| +- org.junit.jupiter:junit-jupiter:jar:5.8.2:test
| | - org.junit.jupiter:junit-jupiter-params:jar:5.8.2:test
| +- org.skyscreamer:jsonassert:jar:1.5.0:test
| | - com.vaadin.external.google:android-json:jar:0.0.20131108.vaadin1:test
| +- org.springframework:spring-test:jar:5.3.10:test
| - org.xmlunit:xmlunit-core:jar:2.8.2:test
+- org.junit.jupiter:junit-jupiter-engine:jar:5.8.2:test
| +- org.junit.platform:junit-platform-engine:jar:1.8.2:test
| | +- org.opentest4j:opentest4j:jar:1.2.0:test
| | - org.junit.platform:junit-platform-commons:jar:1.8.2:test
| +- org.junit.jupiter:junit-jupiter-api:jar:5.8.2:test
| - org.apiguardian:apiguardian-api:jar:1.1.2:test
+- org.mockito:mockito-junit-jupiter:jar:4.1.0:test
| - org.mockito:mockito-core:jar:2.24.0:test
| +- net.bytebuddy:byte-buddy-agent:jar:1.10.22:test
| - org.objenesis:objenesis:jar:2.6:test
+- org.springframework.boot:spring-boot-devtools:jar:2.5.5:compile (optional)
+- net.bytebuddy:byte-buddy-dep:jar:1.12.3:compile
| +- org.ow2.asm:asm:jar:9.2:compile
| - org.ow2.asm:asm-commons:jar:9.2:compile
- com.google.code.gson:gson:jar:2.8.9:compile