Avoid NullPointerException in OpenRewriteMethod

[xiaowu2012]

Caused by: java.lang.NullPointerException: Cannot invoke "org.openrewrite.java.tree.JavaType$FullyQualified.getFullyQualifiedName()" because the return value of "org.openrewrite.java.tree.TypeUtils.asFullyQualified(org.openrewrite.java.tree.JavaType)" is null

Current Version:

 @Override
    public Optional<String> getReturnValue() {
        TypeTree returnTypeExpression = getMethodDecl().getReturnTypeExpression();
        if (returnTypeExpression == null || returnTypeExpression.getType() == JavaType.Primitive.Void) {
            return Optional.empty();
        }

        return Optional.of(TypeUtils.asFullyQualified(returnTypeExpression.getType()).getFullyQualifiedName());
    }

Fixed version:

  @Override
    public Optional<String> getReturnValue() {
        TypeTree returnTypeExpression = getMethodDecl().getReturnTypeExpression();
        if (returnTypeExpression == null || returnTypeExpression.getType() == JavaType.Primitive.Void) {
            return Optional.empty();
        }

        JavaType.FullyQualified jfq = TypeUtils.asFullyQualified(returnTypeExpression.getType());
        if(jfq == null ) {
            return Optional.empty();
        } else {
            return Optional.of(jfq.getFullyQualifiedName());
        }
    }

[fabapp2]

Hi @xiaowu2012
Thanks for the proposed improvement. 🚀
Could you maybe contribute with a test?

[sanagaraj-pivotal]

This is fixed now: #750