error with xsd: import using subdirectories in schemaLocation

[hein4daddel]

Hello,
first thanks for the very fast response on issue #24! Everything s fine, just left a star.
But I found another problem while parsing a xsd with subdirectories: I attached a example zip to reproduce the problem.
issue28_xsd.zip
Parsing the issue_28.xsd shows a

java.lang.NullPointerException
	at org.xmlet.xsdparser.core.XsdParserCore.lambda$null$7(XsdParserCore.java:144)
	at java.util.stream.ForEachOps$ForEachOp$OfRef.accept(ForEachOps.java:183)
	at java.util.stream.ReferencePipeline$2$1.accept(ReferencePipeline.java:175)
	at java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1382)
	at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:482)
	at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:472)
	at java.util.stream.ForEachOps$ForEachOp.evaluateSequential(ForEachOps.java:150)
	at java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(ForEachOps.java:173)
	at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
	at java.util.stream.ReferencePipeline.forEach(ReferencePipeline.java:485)
	at org.xmlet.xsdparser.core.XsdParserCore.lambda$resolveOtherNamespaceRefs$8(XsdParserCore.java:123)
	at java.util.HashMap$KeySet.forEach(HashMap.java:933)

using 1.0.33-SNAPSHOT.
The problem is the import of issue_28b.xsd from issue_28.xsd (with subdirectory issue_28) and from issue_28a.xsd (without subdirectory). If the schemaLocation is specified with an absolute file, it's working.
I looked in the source code and found

    private Map<String, List<ReferenceBase>> parseElements = new HashMap<>();
    private Map<String, List<UnsolvedReference>> unsolvedElements = new HashMap<>();
    List<String> schemaLocations = new ArrayList<>();
    Map<String, String> schemaLocationsMap = new HashMap<>();
    protected String currentFile;

After debugging I saw, thew the keys in schemaLocations sometimes have the directory in it, sometimes not. So I'd suggest using URI instead:

    private Map<URL, List<ReferenceBase>> parseElements = new HashMap<>();
    private Map<URL, List<UnsolvedReference>> unsolvedElements = new HashMap<>();
    List<URL> schemaLocations = new ArrayList<>();
    protected URL currentFile;

because the URLs are normalized. (The schemaLocationsMap not necessary an more). Instead of string manipulation to create a new filename, using
url = new URL(currentFile, importedFileName);
is easier.

If I can help you with more explanations or java code, please let me know.

[lcduarte]

Hello,

Thanks for the star! Also sorry for taking so long this time around.

I probably need to improve the way I work with files, but for now I solved your issue with a temporary solution. I tested with your use case and it didn't give me any errors parsing. A new release is available, (1.1.0), with the fix.

I'll try to improve XsdParser with your suggestion once I have some more free time. Or if you are up to it you can create a pull request with your solution and I'll give it a look. Either way, thanks for the feedback!