Annotate generated sources with @Generated?

I’m compiling my artifact with Java 8, and using the Error Prone compiler plugin. It’s generating a warning because of the following generated code:

MockMvcRequestSpecification request = given()
  .body(new String(fileToBytes(this, "shouldReturnRenderResponseSuccess_request_renderRequest.json")));

The corresponding section of the contract looks like this:

  request {
    method POST()
    url "/render"
    body(file("renderRequest.json")) // this generates the code that fails the error-prone check

The error-prone warning looks like this:

[WARNING] /Users/steve.kingsland/.../My_contractTest.java:[46,11] [DefaultCharset] Implicit use of the platform default charset, which can result in differing behaviour between JVM executions or incorrect behavior if the encoding of the data source doesn't match expectations.
    (see https://errorprone.info/bugpattern/DefaultCharset)
  Did you mean '.body(new String(fileToBytes(this, "shouldReturnRenderResponseSuccess_request_renderRequest.json"), UTF_8));' or '.body(new String(fileToBytes(this, "shouldReturnRenderResponseSuccess_request_renderRequest.json"), Charset.defaultCharset()));'?

I’ve configured the Maven Java compiler plugin to fail the build if there are warnings, so this fails the build.

I’ve identified the following options to solve this problem:

1. don’t use spring cloud contract;
2. don’t use the error prone compile plugin;
3. use a different charset in the contract than the system default (e.g. ASCII), so it will pass the charset to the new String() call and thus won’t trigger an error prone warning;
4. configure error prone to ignore the generated source code from spring cloud contract (e.g. via -XepExcludedPaths:.*/generated-test-sources/.*);
5. configure error prone to ignore all generated source code, via -XepDisableWarningsInGeneratedCode

Has anyone else run into this problem? I think option 5) is probably my best bet, but it requires that the SCC generated classes are annotated with @javax.annotation.Generated or @javax.annotation.processing.Generated. Is that reasonable?

[skingsland]

Yeah, I actually considered doing exactly that, thanks! That’s what I was referring to when I wrote:

1. use a different charset in the contract than the system default (e.g. ASCII), so it will pass the charset to the new String() call and thus won’t trigger an error prone warning;

I didn’t do that because it feels like a workaround that’s a bit hacky, and also I wasn’t sure if there would be any characters in the various renderRequest.json files that we use in this test that aren’t in the UTF-8 character set, and there might be more than one place . So I ended up using the -XepExcludedPaths:.*/generated-test-sources/.* approach instead, and that’s working great.

[marcingrzejszczak]

We could link it with https://github.com/spring-cloud/spring-cloud-contract/issues/1401 and automatically add the Generated annotation to be added.