`NullPointerException` (NPE) in `NestedEnumsAreNotStatic`

[greg-at-moderne]

What version of OpenRewrite are you using?

8.67.1

How are you running OpenRewrite?

Moderne CLI

What is the smallest, simplest way to reproduce the problem?

mod run . --recipe CommonStaticAnalysis against https://github.com/awslabs/aws-saas-boost

What is the full stack trace of any errors you encountered?

"java.lang.NullPointerException: Cannot invoke "org.openrewrite.java.tree.J$Block.getPrefix()" because the return value of "org.openrewrite.java.tree.J$ClassDeclaration.getBody()" is null
  org.openrewrite.java.format.SpacesVisitor.visitClassDeclaration(SpacesVisitor.java:722)
  org.openrewrite.java.format.SpacesVisitor.visitClassDeclaration(SpacesVisitor.java:42)
  org.openrewrite.java.tree.J$ClassDeclaration.acceptJava(J.java:1370)
  org.openrewrite.java.tree.J.accept(J.java:55)
  org.openrewrite.TreeVisitor.visit(TreeVisitor.java:242)
  org.openrewrite.java.format.SpacesVisitor.visit(SpacesVisitor.java:741)
  org.openrewrite.java.format.SpacesVisitor.visit(SpacesVisitor.java:42)
  org.openrewrite.TreeVisitor.visit(TreeVisitor.java:154)
  org.openrewrite.TreeVisitor.visitNonNull(TreeVisitor.java:173)
  org.openrewrite.java.format.AutoFormatVisitor.visit(AutoFormatVisitor.java:74)
  org.openrewrite.java.format.AutoFormatVisitor.visit(AutoFormatVisitor.java:34)
  org.openrewrite.java.JavaVisitor.autoFormat(JavaVisitor.java:95)
  org.openrewrite.java.JavaVisitor.maybeAutoFormat(JavaVisitor.java:76)
  org.openrewrite.java.JavaVisitor.maybeAutoFormat(JavaVisitor.java:71)
  org.openrewrite.java.JavaVisitor.maybeAutoFormat(JavaVisitor.java:67)
  org.openrewrite.staticanalysis.NestedEnumsAreNotStatic$1.visitClassDeclaration(NestedEnumsAreNotStatic.java:66)
  ..."

for https://github.com/awslabs/aws-saas-boost/blob/452d7ca8902e7338e999290eebad9062c342915f/metrics-analytics/metrics-java-sdk/src/main/java/com/amazonaws/saas/metrics/MetricEvent.java

[timtebeek]

This looks to fail in openrewrite/rewrite, on a body field that may not be null. I doubt it's specific to rewrite-static-analysis; should we move the issue?

https://github.com/openrewrite/rewrite/blob/fbfc6e3e5d0cd5cbf62d9280b2a5ebfa45a974d1/rewrite-java/src/main/java/org/openrewrite/java/format/SpacesVisitor.java#L720-L722

I've tried briefly to see if perhaps a combination of recipes triggers this issue, but no such luck just yet, as this test passes.

@Issue("https://github.com/openrewrite/rewrite-static-analysis/issues/796")
@Test
void nestedEnumSemicolons() {
    rewriteRun(
      spec -> spec.recipes(
        new RemoveExtraSemicolons(),
        new NestedEnumsAreNotStatic()
      ),
      //language=java
      java(
        """
          public class Outer {
              static enum Inner {
                  BANANA,
                  APPLE;
              }
          }
          """,
        """
          public class Outer {
              enum Inner {
                  BANANA,
                  APPLE
              }
          }
          """
      )
    );
}

[timtebeek]

I've simplified the associate recipe a bit, but still don't know if that would fix the case we've seen here: 736160d