Fix determination of resource paths from base path and resource name.
Description
The ResourcesConfigurationManager manipulates resource paths manually rather than using e.g. the Path interface. When a base resource path is used with a resource filename, it ensures that the base path ends with a slash, e.g. /com/example/. But the logic for appending the resource name erroneously adds an extra slash, so that a resource name of FooBar-config, for example, results in a search for:
/com/example//FooBar-config.properties.xml
/com/example//FooBar-config.properties
Interestingly this works on Windows 10 when the class path is on the file system. This must be why the bug didn't show up earlier. But when retrieved from inside a JAR file, it fails (as it would be expected to do) with the double-slash.
Environment
None
