refactor(cyclonedx): Avoid exceptions to be swallowed

The BOM generator's `toString()` implementations swallow exceptions [1].
Work around that by calling the underlying functions directly.

[1]: https://github.com/CycloneDX/cyclonedx-core-java/blob/bee058458caed9e966021a1e09c56dd3bb331f46/src/main/java/org/cyclonedx/generators/xml/BomXmlGenerator.java#L141-L149

Signed-off-by: Sebastian Schuberth <sebastian@doubleopen.org>

plugins/reporters/cyclonedx/src/main/kotlin/CycloneDxReporter.kt

@@ -368,8 +368,8 @@ class CycloneDxReporter : Reporter {
         outputFileExtensions.forEach { fileExtension ->
             val outputFile = outputDir.resolve("$outputName.$fileExtension")
 
-            val bomGenerator = when (fileExtension) {
-                "xml" -> BomGeneratorFactory.createXml(schemaVersion, bom)
+            val bom = when (fileExtension) {
+                "xml" -> BomGeneratorFactory.createXml(schemaVersion, bom).toXmlString()
                 "json" -> {
                     // JSON output cannot handle extensible types (see [1]), so simply remove them. As JSON output is
                     // guaranteed to be the last format serialized, it is okay to modify the BOM here without doing a
@@ -391,13 +391,13 @@ class CycloneDxReporter : Reporter {
                         }
                     }
 
-                    BomGeneratorFactory.createJson(schemaVersion, bomWithoutExtensibleTypes)
+                    BomGeneratorFactory.createJson(schemaVersion, bomWithoutExtensibleTypes).toJsonString()
                 }
 
                 else -> throw IllegalArgumentException("Unsupported CycloneDX file extension '$fileExtension'.")
             }
 
-            outputFile.bufferedWriter().use { it.write(bomGenerator.toString()) }
+            outputFile.bufferedWriter().use { it.write(bom) }
             writtenFiles += outputFile
         }