YAML-Headers with Integers not parsing

[FelixAuer]

Problem:

Using this header:

Content-Length: 0

results in HTTP-Request not working with the following error:

Failed executing node plugin [edu.ohio.ais.rundeck.HttpWorkflowNodeStepPlugin] on node XXX: java.lang.ClassCastException: class java.lang.Integer cannot be cast to class java.lang.String (java.lang.Integer and java.lang.String are in module java.base of loader 'bootstrap')
	at edu.ohio.ais.rundeck.HttpBuilder.setHeaders(HttpBuilder.java:456)
	at edu.ohio.ais.rundeck.HttpWorkflowNodeStepPlugin.executeNodeStep(HttpWorkflowNodeStepPlugin.java:118)
	at com.dtolabs.rundeck.core.execution.workflow.steps.node.NodeStepPluginAdapter.executeNodeStep(NodeStepPluginAdapter.java:169)
	at com.dtolabs.rundeck.core.execution.ExecutionServiceImpl.executeNodeStep(ExecutionServiceImpl.java:207)
	at com.dtolabs.rundeck.core.execution.dispatch.SequentialNodeDispatcher.dispatch(SequentialNodeDispatcher.java:130)
	at com.dtolabs.rundeck.core.execution.dispatch.SequentialNodeDispatcher.dispatch(SequentialNodeDispatcher.java:61)
	at com.dtolabs.rundeck.core.execution.ExecutionServiceImpl.dispatchToNodesWith(ExecutionServiceImpl.java:263)
	at com.dtolabs.rundeck.core.execution.ExecutionServiceImpl.dispatchToNodes(ExecutionServiceImpl.java:234)
	at com.dtolabs.rundeck.core.execution.workflow.steps.NodeDispatchStepExecutor.executeWorkflowStep(NodeDispatchStepExecutor.java:66)
	at com.dtolabs.rundeck.core.execution.ExecutionServiceImpl.executeStep(ExecutionServiceImpl.java:111)
	at com.dtolabs.rundeck.core.execution.workflow.BaseWorkflowExecutor.executeWFItem(BaseWorkflowExecutor.java:285)
	at com.dtolabs.rundeck.core.execution.workflow.BaseWorkflowExecutor.executeWorkflowStep(BaseWorkflowExecutor.java:681)
	at com.dtolabs.rundeck.core.execution.workflow.engine.StepCallable.apply(StepCallable.java:71)
	at com.dtolabs.rundeck.core.execution.workflow.engine.StepOperation.apply(StepOperation.java:76)
	at com.dtolabs.rundeck.core.execution.workflow.engine.StepOperation.apply(StepOperation.java:32)
	at com.dtolabs.rundeck.core.rules.WorkflowEngineOperationsProcessor.lambda$beginOperation$1(WorkflowEngineOperationsProcessor.java:323)
	at com.google.common.util.concurrent.TrustedListenableFutureTask$TrustedFutureInterruptibleTask.runInterruptibly(TrustedListenableFutureTask.java:131)
	at com.google.common.util.concurrent.InterruptibleTask.run(InterruptibleTask.java:75)
	at com.google.common.util.concurrent.TrustedListenableFutureTask.run(TrustedListenableFutureTask.java:82)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
	at java.base/java.lang.Thread.run(Thread.java:829)
Failed: PluginFailed: class java.lang.Integer cannot be cast to class java.lang.String (java.lang.Integer and java.lang.String are in module java.base of loader 'bootstrap')

How to replicate

Create a HTTP-Request with the header

Content-Length: 0

results in the error above.

Using

Content-Length: '0'

works.

Additional Information

I suspect the issue was introduced with this PR by @chrismcg14

I think explicitly converting non-string values to strings should resolve the issue.

@chrismcg14: Maybe you can find the time and energy to try this fix, as it would probably take me quite some time to set up a dev environment, as I haven't worked with Java in over 10 years.