In some (as yet unexplained situations) the json form data when adding credentials is garbage.

Steps to Reproduce


	
clone the ATH
	
-checkout https://github.com/jenkinsci/acceptance-test-harness/pull/2221/commits/e18af6bd2825976317b16d594eceb5f7a1f5e3b3- (reproduced on master a4614ed07301ae1b33582b780cca41ad90f111b2)
	
configure your ATH env
	
set INTERACTIVE MODE (export INTERACTIVE=true)
	
mvn clean test -Dtest=SshSlavesPluginTest#newAgent



Expected Results


	
test passes reliably



Actual Results

in some cases the test fails as the submitted json is broken,

e.g. 


------geckoformboundarydcb5b5e50fbcbf4c6b8b778cf6b754f6
Content-Disposition: form-data; name="json"

{"domain":"_","":["1",""],"credentials":{"scope":["GLOBAL","GLOBAL"],"username":["user1",""],"usernameSecret":[false,false],"password":"","$redact":["password","passphrase"],"id":["",""],"description":["Ssh key",""],"privateKeySource":{"value":"0","privateKey":"1212122112","$redact":"privateKey","stapler-class":"com.cloudbees.jenkins.plugins.sshcredentials.impl.BasicSSHUserPrivateKey$DirectEntryPrivateKeySource","$class":"com.cloudbees.jenkins.plugins.sshcredentials.impl.BasicSSHUserPrivateKey$DirectEntryPrivateKeySource"},"passphrase":"","stapler-class":"com.cloudbees.jenkins.plugins.sshcredentials.impl.BasicSSHUserPrivateKey","$class":"com.cloudbees.jenkins.plugins.sshcredentials.impl.BasicSSHUserPrivateKey"},"Jenkins-Crumb":"5f57c3863f722e8911937f70b05c7f385376d795b2d5b004eec8e4a8ae32e50d"}
------geckoformboundarydcb5b5e50fbcbf4c6b8b778cf6b754f6--


Note that the values of many paramters (like scope) are doubled up.
The following error is shown in the Jenkins logs

2025-10-28 21:15:25.173+0000 [id=78]	WARNING	c.c.p.c.CredentialsSelectHelper$WrappedCredentialsStore#doAddCredentials: Failed to create Credentials
org.kohsuke.stapler.WrongTypeException: Got type array but no lister class found for type class com.cloudbees.plugins.credentials.CredentialsScope
	at org.kohsuke.stapler.RequestImpl$TypePair.convertJSON(RequestImpl.java:917)
Caused: java.lang.IllegalArgumentException: Failed to convert the scope parameter of the constructor public com.cloudbees.jenkins.plugins.sshcredentials.impl.BasicSSHUserPrivateKey(com.cloudbees.plugins.credentials.CredentialsScope,java.lang.String,java.lang.String,com.cloudbees.jenkins.plugins.sshcredentials.impl.BasicSSHUserPrivateKey$PrivateKeySource,java.lang.String,java.lang.String)
	at org.kohsuke.stapler.RequestImpl.instantiate(RequestImpl.java:1010)
	at org.kohsuke.stapler.RequestImpl$TypePair.convertJSON(RequestImpl.java:866)
Caused: java.lang.IllegalArgumentException: Failed to instantiate class com.cloudbees.jenkins.plugins.sshcredentials.impl.BasicSSHUserPrivateKey from {"scope":["GLOBAL","GLOBAL"],"username":["user1",""],"usernameSecret":[false,false],"password":"[value redacted]","$redact":["password","passphrase"],"id":["",""],"description":["Ssh key",""],"privateKeySource":{"value":"0","privateKey":"[value redacted]","$redact":"privateKey","stapler-class":"com.cloudbees.jenkins.plugins.sshcredentials.impl.BasicSSHUserPrivateKey$DirectEntryPrivateKeySource","$class":"com.cloudbees.jenkins.plugins.sshcredentials.impl.BasicSSHUserPrivateKey$DirectEntryPrivateKeySource"},"passphrase":"[value redacted]","stapler-class":"com.cloudbees.jenkins.plugins.sshcredentials.impl.BasicSSHUserPrivateKey","$class":"com.cloudbees.jenkins.plugins.sshcredentials.impl.BasicSSHUserPrivateKey"}
	at org.kohsuke.stapler.RequestImpl$TypePair.convertJSON(RequestImpl.java:870)
	at org.kohsuke.stapler.RequestImpl.bindJSON(RequestImpl.java:633)
	at org.kohsuke.stapler.RequestImpl.bindJSON(RequestImpl.java:628)
	at hudson.model.Descriptor.bindJSON(Descriptor.java:662)
	at hudson.model.Descriptor.newInstanceImpl(Descriptor.java:620)
Caused: java.lang.LinkageError: Failed to instantiate class com.cloudbees.jenkins.plugins.sshcredentials.impl.BasicSSHUserPrivateKey from {"scope":["GLOBAL","GLOBAL"],"username":["user1",""],"usernameSecret":[false,false],"password":"[value redacted]","$redact":["password","passphrase"],"id":["",""],"description":["Ssh key",""],"privateKeySource":{"value":"0","privateKey":"[value redacted]","$redact":"privateKey","stapler-class":"com.cloudbees.jenkins.plugins.sshcredentials.impl.BasicSSHUserPrivateKey$DirectEntryPrivateKeySource","$class":"com.cloudbees.jenkins.plugins.sshcredentials.impl.BasicSSHUserPrivateKey$DirectEntryPrivateKeySource"},"passphrase":"[value redacted]","stapler-class":"com.cloudbees.jenkins.plugins.sshcredentials.impl.BasicSSHUserPrivateKey","$class":"com.cloudbees.jenkins.plugins.sshcredentials.impl.BasicSSHUserPrivateKey"}
	at hudson.model.Descriptor.newInstanceImpl(Descriptor.java:626)
	at hudson.model.Descriptor.newInstance(Descriptor.java:594)
	at hudson.model.Descriptor$NewInstanceBindInterceptor.instantiate(Descriptor.java:709)
	at org.kohsuke.stapler.RequestImpl.instantiate(RequestImpl.java:980)
	at org.kohsuke.stapler.RequestImpl$TypePair.convertJSON(RequestImpl.java:866)
	at org.kohsuke.stapler.RequestImpl.bindJSON(RequestImpl.java:633)
	at org.kohsuke.stapler.RequestImpl.bindJSON(RequestImpl.java:628)
	at hudson.model.Descriptor.bindJSON(Descriptor.java:662)
	at hudson.model.Descriptor.bindJSON(Descriptor.java:637)
	at PluginClassLoader for credentials//com.cloudbees.plugins.credentials.CredentialsSelectHelper$WrappedCredentialsStore.doAddCredentials(CredentialsSelectHelper.java:609)


Whilst there is currently no HAR to show this faulty submission, you can start the devtools and enable HAR recording once the test has started (and hope you are lucky that you catch the failure!)
Seems to fail about 1 in 10 for me - failed in the ATH job which reruns failed tests twice.
https://github.com/jenkinsci/acceptance-test-harness/pull/2221/checks?check_run_id=53913818869