Fix issue parsing string with Java8ReloadableParser

[rlsanders4]

What's changed?

Revert the Java8ReloadableParser to use JavaCompiler.parse() instead of JavaCompiler.parseFiles() to support parsing strings as input. This issue does not occur with other versions of the Java parser.

What's your motivation?

Recent changes to Java8ReloadableParser caused the following error in our custom recipes:

• Partial support Lombok for java 8 (mostly done) #4855

SEVERE: java.lang.IndexOutOfBoundsException: Index: 0, Size: 0
	at com.sun.tools.javac.util.List.get(List.java:476)
	at org.openrewrite.java.ReloadableJava8Parser.parseInputsToCompilerAst(ReloadableJava8Parser.java:260)
	at org.openrewrite.java.ReloadableJava8Parser.parseInputs(ReloadableJava8Parser.java:211)
	at org.openrewrite.java.Java8Parser.parseInputs(Java8Parser.java:44)
	at org.openrewrite.java.JavaParser.parse(JavaParser.java:285)
	at org.openrewrite.java.JavaParser.parse(JavaParser.java:300)

This occurs when we attempt to parse a file from a string input:

                        Path targetFile = Paths.get("/path/to/file.java")

                        Stream<SourceFile> sourceJavaFile = JavaParser.fromJavaVersion()
                                .build()
                                .parse(new String(Files.readAllBytes(targetFile)));

Anyone you would like to review specifically?

@timtebeek

Any additional context

I would like to add a unit test for this, but I have not been able to figure out how to make calls to JavaParser.fromJavaVersion().build().parse() using Java 8 within the unit testing framework. Any assistance with this would be appreciated. I have confirmed this change fixes our recipes through end-to-end testing.

Checklist

• I've added unit tests to cover both positive and negative cases
• I've read and applied the recipe conventions and best practices
• I've used the IntelliJ IDEA auto-formatter on affected files

[timtebeek]

Looks ok from my end when compared to the line removed previously. I wouldn't necessarily know how to best test this, but I would be fine merging this without another test.
/cc @knutwannheden in case I missed anything

[knutwannheden]

I added a test case to rewrite-java-tck which I think should have been able to reproduce the issue as this will be executed for rewrite-java-8 which uses a Java 1.8 VM. I was not able to reproduce the issue, but I don't see any harm with this PR either. Possibly we can get the test case working at some point.