Trying to execute the very first example for pipeline fails with:
2021-05-26T14:31:05.445 ERROR AnchoreWorker Failed to add image(s) to anchore-engine due to an unexpected error
java.lang.ClassCastException: [B cannot be cast to java.lang.String
at org.apache.http.conn.ssl.DefaultHostnameVerifier.getSubjectAltNames(DefaultHostnameVerifier.java:309)
at org.apache.http.conn.ssl.DefaultHostnameVerifier.verify(DefaultHostnameVerifier.java:112)
at org.apache.http.conn.ssl.DefaultHostnameVerifier.verify(DefaultHostnameVerifier.java:99)
at org.apache.http.conn.ssl.SSLConnectionSocketFactory.verifyHostname(SSLConnectionSocketFactory.java:463)
at org.apache.http.conn.ssl.SSLConnectionSocketFactory.createLayeredSocket(SSLConnectionSocketFactory.java:397)
at org.apache.http.conn.ssl.SSLConnectionSocketFactory.connectSocket(SSLConnectionSocketFactory.java:355)
at org.apache.http.impl.conn.DefaultHttpClientConnectionOperator.connect(DefaultHttpClientConnectionOperator.java:142)
at org.apache.http.impl.conn.PoolingHttpClientConnectionManager.connect(PoolingHttpClientConnectionManager.java:359)
at org.apache.http.impl.execchain.MainClientExec.establishRoute(MainClientExec.java:381)
at org.apache.http.impl.execchain.MainClientExec.execute(MainClientExec.java:237)
at org.apache.http.impl.execchain.ProtocolExec.execute(ProtocolExec.java:185)
at org.apache.http.impl.execchain.RetryExec.execute(RetryExec.java:89)
at org.apache.http.impl.execchain.RedirectExec.execute(RedirectExec.java:111)
at org.apache.http.impl.client.InternalHttpClient.doExecute(InternalHttpClient.java:185)
at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:83)
at com.anchore.jenkins.plugins.anchore.BuildWorker.runAnalyzerEngine(BuildWorker.java:264)
at com.anchore.jenkins.plugins.anchore.BuildWorker.runAnalyzer(BuildWorker.java:173)
at com.anchore.jenkins.plugins.anchore.AnchoreBuilder.perform(AnchoreBuilder.java:242)
at jenkins.tasks.SimpleBuildStep.perform(SimpleBuildStep.java:123)
at org.jenkinsci.plugins.workflow.steps.CoreStep$Execution.run(CoreStep.java:99)
at org.jenkinsci.plugins.workflow.steps.CoreStep$Execution.run(CoreStep.java:69)
at org.jenkinsci.plugins.workflow.steps.SynchronousNonBlockingStepExecution.lambda$start$0(SynchronousNonBlockingStepExecution.java:47)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)
2021-05-26T14:31:05.445 ERROR AnchorePlugin Failing Anchore Container Image Scanner Plugin step due to errors in plugin execution
hudson.AbortException: Failed to add image(s) to anchore-engine due to an unexpected error. Please refer to above logs for more information
at com.anchore.jenkins.plugins.anchore.BuildWorker.runAnalyzerEngine(BuildWorker.java:297)
at com.anchore.jenkins.plugins.anchore.BuildWorker.runAnalyzer(BuildWorker.java:173)
at com.anchore.jenkins.plugins.anchore.AnchoreBuilder.perform(AnchoreBuilder.java:242)
at jenkins.tasks.SimpleBuildStep.perform(SimpleBuildStep.java:123)
at org.jenkinsci.plugins.workflow.steps.CoreStep$Execution.run(CoreStep.java:99)
at org.jenkinsci.plugins.workflow.steps.CoreStep$Execution.run(CoreStep.java:69)
at org.jenkinsci.plugins.workflow.steps.SynchronousNonBlockingStepExecution.lambda$start$0(SynchronousNonBlockingStepExecution.java:47)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)

The problem looks to be httpclient 4.5.3: https://issues.apache.org/jira/browse/HTTPCLIENT-1836