[UNDERTOW-1821] Path template matched parameters should keep order

[seregamorph]

Jira: https://issues.redhat.com/browse/UNDERTOW-1821

Replace HashMap to LinkedHashMap in PathTemplateMatcher. Motivation: ordered matched paths look more natural e.g. in debugging:

Also in my case I needed to write a simple custom matcher: not Map (expected) equals Map (actual), but a List of matched values (cannot use Set, because values can be repeated).

Reference implementation: spring-core org.springframework.util.AntPathMatcher keeps original order:

AntPathMatcher antPathMatcher = new AntPathMatcher();
Map<String, String> pathVariables = antPathMatcher.extractUriTemplateVariables(
        "/{context}/{version}/{controller}/{id}",
        "/api/v3/users/1"
);
// prints "{context=api, version=v3, controller=users, id=1}"

Cons: in theory, updated impl will take more nanoseconds in runtime and more nanobytes in memory, but I believe if there was an intention to micro-optimise it, these should be a custom Map implementation (like Netty HttpHeaders)

[seregamorph]

@stuartwdouglas what do you think?

[fl4via]

@seregamorph we are approving this change. The advantage of keeping parameters in order outweights the added overhead, specially because hte matcher's map is small and is not used every where in the code.

[seregamorph]

Thanks @fl4via