Upgrade to Gson 2.8.4

[wilkinsona]

No description provided.

[wilkinsona]

GSON 2.8.3 and 2.8.4 don't work on Java 9 on Debian due to a parsing failure when trying to determine the major Java version:

java.lang.ExceptionInInitializerError
	at com.google.gson.internal.reflect.ReflectionAccessor.<clinit>(ReflectionAccessor.java:36)
	at com.google.gson.internal.ConstructorConstructor.<init>(ConstructorConstructor.java:51)
	at com.google.gson.Gson.<init>(Gson.java:205)
	at com.google.gson.GsonBuilder.create(GsonBuilder.java:597)
	at org.springframework.boot.json.GsonJsonParser.<init>(GsonJsonParser.java:40)
	at org.springframework.boot.json.GsonJsonParserTests.getParser(GsonJsonParserTests.java:28)
	at org.springframework.boot.json.AbstractJsonParserTests.<init>(AbstractJsonParserTests.java:40)
	at org.springframework.boot.json.GsonJsonParserTests.<init>(GsonJsonParserTests.java:24)
	at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
	at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
	at java.base/jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
	at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:488)
	at org.junit.runners.BlockJUnit4ClassRunner.createTest(BlockJUnit4ClassRunner.java:217)
	at org.junit.runners.BlockJUnit4ClassRunner$1.runReflectiveCall(BlockJUnit4ClassRunner.java:266)
	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
	at org.junit.runners.BlockJUnit4ClassRunner.methodBlock(BlockJUnit4ClassRunner.java:263)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
	at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
	at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
	at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
	at org.apache.maven.surefire.junit4.JUnit4Provider.execute(JUnit4Provider.java:365)
	at org.apache.maven.surefire.junit4.JUnit4Provider.executeWithRerun(JUnit4Provider.java:273)
	at org.apache.maven.surefire.junit4.JUnit4Provider.executeTestSet(JUnit4Provider.java:238)
	at org.apache.maven.surefire.junit4.JUnit4Provider.invoke(JUnit4Provider.java:159)
	at org.apache.maven.surefire.booter.ForkedBooter.invokeProviderInSameClassLoader(ForkedBooter.java:379)
	at org.apache.maven.surefire.booter.ForkedBooter.runSuitesInProcess(ForkedBooter.java:340)
	at org.apache.maven.surefire.booter.ForkedBooter.execute(ForkedBooter.java:125)
	at org.apache.maven.surefire.booter.ForkedBooter.main(ForkedBooter.java:413)
Caused by: java.lang.NumberFormatException: For input string: "9-Debian"
	at java.base/java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
	at java.base/java.lang.Integer.parseInt(Integer.java:652)
	at java.base/java.lang.Integer.parseInt(Integer.java:770)
	at com.google.gson.util.VersionUtils.determineMajorJavaVersion(VersionUtils.java:28)
	at com.google.gson.util.VersionUtils.<clinit>(VersionUtils.java:24)
	... 32 more

[wilkinsona]

I've reported the GSON issue here. I've also upgraded our CI to use a more up-to-date JDK 9 image just in case (and I think it's very unlikely) it's changed the format of the java.version property's value.

[wilkinsona]

To my surprise, the JDK 9 upgrade has resolved the problem.