Merge branch 'versionnull' into 3.1rc3

Author: terriko

cve_bin_tool/version_scanner.py

@@ -236,6 +236,11 @@ def run_java_checker(self, filename: str) -> Iterator[ScanInfo]:
                 version = root.find(schema + "version").text
             if version is None and parent is not None:
                 version = parent.find(schema + "version").text
+
+            # If all else fails, set version to UNKNOWN
+            if version is None:
+                version = "UNKNOWN"
+
             # Check valid version identifier (i.e. starts with a digit)
             if not version[0].isdigit():
                 self.logger.debug(f"Invalid {version} detected in {filename}")