Mule ESB and the NoSuchMethodError: org.mule.util.ClassUtils.getClass exception

Currently I am adding some SAML related functionality to a Mule3 implementation of one of our clients. To work with the SAML objects I make use of the OpenSAML library that is provided here as open source.

I added the following dependencies to my pom.xml to make it work:

<!-- SAML dependencies -->
<dependency>
  <groupId>org.opensaml</groupId>
  <artifactId>opensaml</artifactId>
  <version>2.5.1-1</version>
</dependency>
<dependency>
  <groupId>joda-time</groupId>
  <artifactId>joda-time</artifactId>
  <version>2.1</version>
</dependency>
<dependency>
  <groupId>org.opensaml</groupId>
  <artifactId>openws</artifactId>
  <version>1.4.2-1</version>
</dependency>
<dependency>
  <groupId>org.opensaml</groupId>
  <artifactId>xmltooling</artifactId>
  <version>1.3.2-1</version>
  <exclusions>
    <exclusion>
      <artifactId>log4j-over-slf4j</artifactId>
      <groupId>org.slf4j</groupId>
    </exclusion>
  </exclusions>
</dependency>
<dependency>
  <groupId>org.slf4j</groupId>
  <artifactId>slf4j-log4j12</artifactId>
  <version>1.7.2</version>
</dependency>

However, after adding these dependencies and running a test with the Mule instance I received this exception:

java.lang.NoSuchMethodError: org.mule.util.ClassUtils.getClass(Ljava/lang/String;Z)Ljava/lang/Class;
at org.mule.util.ClassUtils.initializeClass(ClassUtils.java:356)
at org.mule.lifecycle.NotificationLifecycleObject.(NotificationLifecycleObject.java:45)
at org.mule.lifecycle.phases.MuleContextStopPhase.(MuleContextStopPhase.java:66)
at org.mule.lifecycle.phases.MuleContextStopPhase.(MuleContextStopPhase.java:56)
at org.mule.lifecycle.RegistryBrokerLifecycleManager.registerPhases(RegistryBrokerLifecycleManager.java:43)
at org.mule.lifecycle.RegistryLifecycleManager.(RegistryLifecycleManager.java:57)
at org.mule.lifecycle.RegistryBrokerLifecycleManager.(RegistryBrokerLifecycleManager.java:33)
at org.mule.registry.AbstractRegistryBroker.(AbstractRegistryBroker.java:37)
at org.mule.registry.DefaultRegistryBroker.(DefaultRegistryBroker.java:27)
at org.mule.DefaultMuleContext.createRegistryBroker(DefaultMuleContext.java:159)
at org.mule.DefaultMuleContext.(DefaultMuleContext.java:150)
at org.mule.context.DefaultMuleContextBuilder.buildMuleContext(DefaultMuleContextBuilder.java:89)
at org.mule.context.DefaultMuleContextFactory.buildMuleContext(DefaultMuleContextFactory.java:199)
at org.mule.context.DefaultMuleContextFactory.doCreateMuleContext(DefaultMuleContextFactory.java:189)
at org.mule.context.DefaultMuleContextFactory.createMuleContext(DefaultMuleContextFactory.java:75)
at org.mule.tck.AbstractMuleTestCase.createMuleContext(AbstractMuleTestCase.java:520)
at org.mule.tck.AbstractMuleTestCase.setUp(AbstractMuleTestCase.java:446)
at junit.framework.TestCase.runBare(TestCase.java:132)
at org.mule.tck.AbstractMuleTestCase.runBare(AbstractMuleTestCase.java:301)
at junit.framework.TestResult$1.protect(TestResult.java:110)
at junit.framework.TestResult.runProtected(TestResult.java:128)
at junit.framework.TestResult.run(TestResult.java:113)
at junit.framework.TestCase.run(TestCase.java:124)
at org.mule.tck.AbstractMuleTestCase.run(AbstractMuleTestCase.java:280)
at junit.framework.TestSuite.runTest(TestSuite.java:232)
at junit.framework.TestSuite.run(TestSuite.java:227)
at org.junit.internal.runners.JUnit38ClassRunner.run(JUnit38ClassRunner.java:83)
at org.apache.maven.surefire.junit4.JUnit4Provider.execute(JUnit4Provider.java:264)
at org.apache.maven.surefire.junit4.JUnit4Provider.executeTestSet(JUnit4Provider.java:153)
at org.apache.maven.surefire.junit4.JUnit4Provider.invoke(JUnit4Provider.java:124)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.apache.maven.surefire.util.ReflectionUtils.invokeMethodWithArray2(ReflectionUtils.java:208)
at org.apache.maven.surefire.booter.ProviderFactory$ProviderProxy.invoke(ProviderFactory.java:158)
at org.apache.maven.surefire.booter.ProviderFactory.invokeProvider(ProviderFactory.java:86)
at org.apache.maven.surefire.booter.ForkedBooter.runSuitesInProcess(ForkedBooter.java:153)
at org.apache.maven.surefire.booter.ForkedBooter.main(ForkedBooter.java:95)

Which was weird because I wouldn’t expect OpenSAML libraries to influence the org.mule.util package! After googling around I discovered that the exception is caused when an older version of Apache commons-lang is being put on the classpath. So by excluding this dependency from the project the issue was fixed:

<dependency>
  <groupId>org.opensaml</groupId>
  <artifactId>opensaml</artifactId>
  <version>2.5.1-1</version>
  <exclusions>
    <exclusion>
      <artifactId>commons-lang</artifactId>
      <groupId>commons-lang</groupId>
    </exclusion>
  </exclusions>
</dependency>

Just too bad that the message looks like to suggest there is something wrong with the Mule libraries. With this exclusion in place the ‘commons-lang-2.1.jar’ is not added to the classpath but the ‘commons-lang-2.4.jar’ which is expected by Mule to be available.