PathPatternParserTests#regexPathElementPatterns() fails on Java 13

[snicoll]

Stacktrace:

org.opentest4j.AssertionFailedError: [/{var:a{{1,2}}}
        ^
Exception occurred in regex pattern compilation] 
Expecting:
 <8>
to be equal to:
 <6>
but was not.
	at jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
	at jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
	at jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
	at java.lang.reflect.Constructor.newInstanceWithCaller(Constructor.java:500)
	at org.springframework.web.util.pattern.PathPatternParserTests.lambda$checkError$3(PathPatternParserTests.java:441)
	at org.springframework.web.util.pattern.PathPatternParserTests.checkError(PathPatternParserTests.java:440)
	at org.springframework.web.util.pattern.PathPatternParserTests.regexPathElementPatterns(PathPatternParserTests.java:121)
	at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:567)
	at org.junit.platform.commons.util.ReflectionUtils.invokeMethod(ReflectionUtils.java:675)

[sbrannen]

After some internal brainstorming...

Proposal

Create an overloaded variant of checkError() for the /{var:a{{1,2}}} pattern that does not check the expectedPos, but leave the remaining usage of checkError() as-is.

Rationale

If a java.util.regex.PatternSyntaxException is thrown, we cannot influence the "error index" reported in that exception. Thus, we should not assert a specific "expected position" in the org.springframework.web.util.pattern.PatternParseException thrown by org.springframework.web.util.pattern.PathPatternParser.parse(String) for such cases.

Research

Potentially caused this change in JDK 13: http://hg.openjdk.java.net/jdk/jdk/rev/7a026580fed5