Expanding UriTemplate with empty collections or empty arrays fails with Java 21

[ckumpe]

We tried to use the UriTemplate in projects using Java 21.
E.g. in https://github.com/wcm-io-caravan/caravan-rhyme

The error can reproduced in this project itself by just building it with Java 21:

1. Update the source code level to 1.8 for the maven-compiler-plugin:

  <plugin>
      <groupId>org.apache.maven.plugins</groupId>
      <artifactId>maven-compiler-plugin</artifactId>
      <version>3.8.1</version>
      <configuration>
          <source>1.8</source>
          <target>1.8</target>
      </configuration>
  </plugin>

2. Run maven package:

$ export JAVA_HOME=/usr/lib/jvm/java-21-openjdk-amd64/
$ ./mvnw clean package

3. This makes the following tests to fail:

[INFO] Results:
[INFO] 
[ERROR] Failures: 
[ERROR]   TestExtendedSpecTests>AbstractUriTemplateConformanceTest.test:156 Additional Examples 3: Empty Variables->  Template: {/empty_list*} returned java.lang.reflect.InvocationTargetException and did not match any combination
[ERROR]   TestExtendedSpecTests>AbstractUriTemplateConformanceTest.test:156 Additional Examples 3: Empty Variables->  Template: {/empty_list} returned java.lang.reflect.InvocationTargetException and did not match any combination
[ERROR]   TestExtendedSpecTests>AbstractUriTemplateConformanceTest.test:156 Additional Examples 3: Empty Variables->  Template: {?empty_list*} returned java.lang.reflect.InvocationTargetException and did not match any combination
[ERROR]   TestExtendedSpecTests>AbstractUriTemplateConformanceTest.test:156 Additional Examples 3: Empty Variables->  Template: {?empty_list} returned java.lang.reflect.InvocationTargetException and did not match any combination
[ERROR]   TestSpecExamplesBySection>AbstractUriTemplateConformanceTest.test:156 3.2.5 Label Expansion with Dot-Prefix->  Template: X{.empty_keys*} returned java.lang.reflect.InvocationTargetException and did not match any combination
[ERROR]   TestSpecExamplesBySection>AbstractUriTemplateConformanceTest.test:156 3.2.5 Label Expansion with Dot-Prefix->  Template: X{.empty_keys} returned java.lang.reflect.InvocationTargetException and did not match any combination
[INFO] 
[ERROR] Tests run: 461, Failures: 6, Errors: 0, Skipped: 7

The issue is caused by new methods added to Java collections in Java 21:

• https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/util/SequencedCollection.html#getFirst()
• https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/util/SequencedCollection.html#getLast()

These methods look like bean properties (named first and last) but throwing a NoSuchElementException if the collection is empty.