unexpected error with SWIFT Package Manager Analyzer

[piggy34]

Describe the bug
Receiving the following error

`
[INFO] Finished SWIFT Package Manager Analyzer (0 seconds)
[WARN] An unexpected error occurred during analysis of '.../Package.resolved' (SWIFT Package Resolved Analyzer): class javax.json.JsonValueImpl cannot be cast to class javax.json.JsonString (javax.json.JsonValueImpl and javax.json.JsonString are in unnamed module of loader 'app')

[ERROR]
java.lang.ClassCastException: class javax.json.JsonValueImpl cannot be cast to class javax.json.JsonString (javax.json.JsonValueImpl and javax.json.JsonString are in unnamed module of loader 'app')
at org.glassfish.json.JsonObjectBuilderImpl$JsonObjectImpl.getJsonString(JsonObjectBuilderImpl.java:252)
at org.glassfish.json.JsonObjectBuilderImpl$JsonObjectImpl.getString(JsonObjectBuilderImpl.java:257)
at org.owasp.dependencycheck.analyzer.SwiftPackageResolvedAnalyzer.lambda$analyzeSpmResolvedDependencies$0(SwiftPackageResolvedAnalyzer.java:175)
at java.base/java.lang.Iterable.forEach(Iterable.java:75)
at org.owasp.dependencycheck.analyzer.SwiftPackageResolvedAnalyzer.analyzeSpmResolvedDependencies(SwiftPackageResolvedAnalyzer.java:168)
at org.owasp.dependencycheck.analyzer.SwiftPackageResolvedAnalyzer.analyzeDependency(SwiftPackageResolvedAnalyzer.java:139)
at org.owasp.dependencycheck.analyzer.AbstractAnalyzer.analyze(AbstractAnalyzer.java:131)
at org.owasp.dependencycheck.AnalysisTask.call(AnalysisTask.java:88)
at org.owasp.dependencycheck.AnalysisTask.call(AnalysisTask.java:37)
at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
at java.base/java.lang.Thread.run(Thread.java:833)

`

Version of dependency-check used
The problem occurs using version 6.5.0 of the cli

To Reproduce
Steps to reproduce the behavior:

1. brew install dependency-check
2. dependency-check --suppression dependency-check-suppression.xml --enableExperimental --project XXX --out . --scan .

Expected behavior
dependency check to run without complaints

[squarefrog]

I'm getting this too with 6.5.0, with a Package.resolved containing null values. For example, try this Package.resolved file:

{
  "object": {
    "pins": [
      {
        "package": "Commandant",
        "repositoryURL": "https://github.com/Carthage/Commandant.git",
        "state": {
          "branch": null,
          "revision": "ab68611013dec67413628ac87c1f29e8427bc8e4",
          "version": "0.17.0"
        }
      },
      {
        "package": "swift-doc",
        "repositoryURL": "https://github.com/SwiftDocOrg/swift-doc",
        "state": {
          "branch": "1.0.0-beta.4",
          "revision": "581af2fe50667ed2f49c53d26b91a8feb4531302",
          "version": null
        }
      }
    ]
  },
  "version": 1
}

Replacing the null value from version causes the error to not be thrown. With SPM, if version is null, then they are using the head of a specific branch.

Looking at this line, should there be a check to see if the value exists before trying to extract it?

[jeremylong]

Thanks for the PR!