When running a Jenkins job, the following error occurs:
java.lang.ClassNotFoundException: org.apache.commons.lang.StringUtils
at java.base/java.net.URLClassLoader.findClass(URLClassLoader.java:445)
at jenkins.util.URLClassLoader2.findClass(URLClassLoader2.java:70)
at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:593)
at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:526)
Caused: java.lang.NoClassDefFoundError: org/apache/commons/lang/StringUtils
at PluginClassLoader for gerrit-code-review//jenkins.plugins.gerrit.AbstractGerritSCMSource$1.run(AbstractGerritSCMSource.java:140)
at PluginClassLoader for gerrit-code-review//jenkins.plugins.gerrit.AbstractGerritSCMSource$1.run(AbstractGerritSCMSource.java:126)
at PluginClassLoader for gerrit-code-review//jenkins.plugins.gerrit.AbstractGerritSCMSource.doRetrieve(AbstractGerritSCMSource.java:691)
at PluginClassLoader for gerrit-code-review//jenkins.plugins.gerrit.AbstractGerritSCMSource.retrieve(AbstractGerritSCMSource.java:124)
at PluginClassLoader for scm-api//jenkins.scm.api.SCMSource.fetch(SCMSource.java:577)
at PluginClassLoader for workflow-multibranch//org.jenkinsci.plugins.workflow.multibranch.SCMBinder.create(SCMBinder.java:104)
at PluginClassLoader for workflow-job//org.jenkinsci.plugins.workflow.job.WorkflowRun.run(WorkflowRun.java:342)
This appears to be a dependency/compatibility issue in gerrit-code-review. The plugin is trying to load the legacy Apache Commons Lang 2.x class org.apache.commons.lang.StringUtils, but that class is not available in the current Jenkins environment.

The installed commons-lang3 plugin provides org.apache.commons.lang3.StringUtils, which is a different package and does not satisfy this dependency.