我有一个类，我试图模仿一个静态方法。我有以下。。。

@PrepareForTest(Client.class)
@RunWith(PowerMockRunner.class)
public class ConfigTest {
   ...
   when(Client.createSession(
                anyString(),
                any(),
                any())).thenReturn(session);
}

但是当我试着跑的时候。。。

java.lang.IllegalStateException: Failed to transform class with name my.pkg.Client. Reason: cannot find javax.servlet.http.HttpSession

    at org.powermock.core.classloader.javassist.JavassistMockClassLoader.defineAndTransformClass(JavassistMockClassLoader.java:119)
    at org.powermock.core.classloader.MockClassLoader.loadMockClass(MockClassLoader.java:174)
    at org.powermock.core.classloader.MockClassLoader.loadClassByThisClassLoader(MockClassLoader.java:102)
    at org.powermock.core.classloader.DeferSupportingClassLoader.loadClass1(DeferSupportingClassLoader.java:147)
    at org.powermock.core.classloader.DeferSupportingClassLoader.loadClass(DeferSupportingClassLoader.java:98)
    at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:521)
    at java.base/java.lang.Class.forName0(Native Method)
    at java.base/java.lang.Class.forName(Class.java:415)
    at java.base/sun.reflect.generics.factory.CoreReflectionFactory.makeNamedType(CoreReflectionFactory.java:114)
    at java.base/sun.reflect.generics.visitor.Reifier.visitClassTypeSignature(Reifier.java:125)
    at java.base/sun.reflect.generics.tree.ClassTypeSignature.accept(ClassTypeSignature.java:49)
    at java.base/sun.reflect.annotation.AnnotationParser.parseSig(AnnotationParser.java:440)
    at java.base/sun.reflect.annotation.AnnotationParser.parseClassValue(AnnotationParser.java:421)
    at java.base/sun.reflect.annotation.AnnotationParser.lambda$parseClassArray$0(AnnotationParser.java:719)
    at java.base/sun.reflect.annotation.AnnotationParser.parseArrayElements(AnnotationParser.java:747)
    at java.base/sun.reflect.annotation.AnnotationParser.parseClassArray(AnnotationParser.java:718)
    at java.base/sun.reflect.annotation.AnnotationParser.parseArray(AnnotationParser.java:532)
    at java.base/sun.reflect.annotation.AnnotationParser.parseMemberValue(AnnotationParser.java:356)
    at java.base/sun.reflect.annotation.AnnotationParser.parseAnnotation2(AnnotationParser.java:287)
    at java.base/sun.reflect.annotation.AnnotationParser.parseAnnotations2(AnnotationParser.java:121)
    at java.base/sun.reflect.annotation.AnnotationParser.parseAnnotations(AnnotationParser.java:73)
    at java.base/java.lang.Class.createAnnotationData(Class.java:3762)
    at java.base/java.lang.Class.annotationData(Class.java:3751)
    at java.base/java.lang.Class.getAnnotation(Class.java:3656)
    at org.junit.internal.MethodSorter.getDeclaredMethods(MethodSorter.java:52)
    at org.junit.internal.runners.TestClass.getAnnotatedMethods(TestClass.java:45)
    at org.junit.internal.runners.MethodValidator.validateTestMethods(MethodValidator.java:71)
    at org.junit.internal.runners.MethodValidator.validateStaticMethods(MethodValidator.java:44)
    at org.junit.internal.runners.MethodValidator.validateMethodsForDefaultRunner(MethodValidator.java:50)
    at org.powermock.modules.junit4.internal.impl.PowerMockJUnit44RunnerDelegateImpl.validate(PowerMockJUnit44RunnerDelegateImpl.java:124)
    at org.powermock.modules.junit4.internal.impl.PowerMockJUnit44RunnerDelegateImpl.<init>(PowerMockJUnit44RunnerDelegateImpl.java:86)
    at org.powermock.modules.junit4.internal.impl.PowerMockJUnit47RunnerDelegateImpl.<init>(PowerMockJUnit47RunnerDelegateImpl.java:42)
    at org.powermock.modules.junit4.internal.impl.PowerMockJUnit49RunnerDelegateImpl.<init>(PowerMockJUnit49RunnerDelegateImpl.java:25)
    at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
    at java.base/jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.base/java.lang.reflect.Constructor.newInstanceWithCaller(Constructor.java:500)
    at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:481)
    at org.powermock.modules.junit4.common.internal.impl.JUnit4TestSuiteChunkerImpl.createDelegatorFromClassloader(JUnit4TestSuiteChunkerImpl.java:165)
    at org.powermock.modules.junit4.common.internal.impl.JUnit4TestSuiteChunkerImpl.createDelegatorFromClassloader(JUnit4TestSuiteChunkerImpl.java:47)
    at org.powermock.tests.utils.impl.AbstractTestSuiteChunkerImpl.createTestDelegators(AbstractTestSuiteChunkerImpl.java:107)
    at org.powermock.modules.junit4.common.internal.impl.JUnit4TestSuiteChunkerImpl.<init>(JUnit4TestSuiteChunkerImpl.java:69)
    at org.powermock.modules.junit4.common.internal.impl.AbstractCommonPowerMockRunner.<init>(AbstractCommonPowerMockRunner.java:36)
    at org.powermock.modules.junit4.PowerMockRunner.<init>(PowerMockRunner.java:34)
    at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
    at java.base/jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.base/java.lang.reflect.Constructor.newInstanceWithCaller(Constructor.java:500)
    at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:481)
    at org.junit.internal.builders.AnnotatedBuilder.buildRunner(AnnotatedBuilder.java:104)
    at org.junit.internal.builders.AnnotatedBuilder.runnerForClass(AnnotatedBuilder.java:86)
    at org.junit.runners.model.RunnerBuilder.safeRunnerForClass(RunnerBuilder.java:70)
    at org.junit.internal.builders.AllDefaultPossibilitiesBuilder.runnerForClass(AllDefaultPossibilitiesBuilder.java:37)
    at org.junit.runners.model.RunnerBuilder.safeRunnerForClass(RunnerBuilder.java:70)
    at org.junit.internal.requests.ClassRequest.createRunner(ClassRequest.java:28)
    at org.junit.internal.requests.MemoizingRequest.getRunner(MemoizingRequest.java:19)
    at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:50)
    at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:33)
    at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:220)
    at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:53)
Caused by: javassist.CannotCompileException: cannot find javax.servlet.http.HttpSession
    at javassist.CtBehavior.insertBefore(CtBehavior.java:803)
    at javassist.CtBehavior.insertBefore(CtBehavior.java:766)
    at org.powermock.core.transformers.javassist.MethodMockTransformer.modifyMethod(MethodMockTransformer.java:114)
    at org.powermock.core.transformers.javassist.MethodMockTransformer.modifyMethod(MethodMockTransformer.java:55)
    at org.powermock.core.transformers.javassist.StaticFinalNativeMethodMockTransformer.transform(StaticFinalNativeMethodMockTransformer.java:37)
    at org.powermock.core.transformers.javassist.AbstractJavaAssistMockTransformer.transform(AbstractJavaAssistMockTransformer.java:40)
    at org.powermock.core.transformers.support.DefaultMockTransformerChain.transform(DefaultMockTransformerChain.java:43)
    at org.powermock.core.classloader.MockClassLoader.transformClass(MockClassLoader.java:184)
    at org.powermock.core.classloader.javassist.JavassistMockClassLoader.defineAndTransformClass(JavassistMockClassLoader.java:102)
    ... 59 more
Caused by: javassist.NotFoundException: javax.servlet.http.HttpSession
    at javassist.ClassPool.get(ClassPool.java:430)
    at javassist.bytecode.Descriptor.toCtClass(Descriptor.java:571)
    at javassist.bytecode.Descriptor.getParameterTypes(Descriptor.java:424)
    at javassist.CtBehavior.getParameterTypes(CtBehavior.java:323)
    at javassist.CtBehavior.insertBefore(CtBehavior.java:781)
    ... 67 more

我不知道这个例外是想说什么，我看不到太多的方式博士。
有人能帮我吗？