Add @Required annotation with optional validator by fst-john · Pull Request #1558 · slackapi/java-slack-sdk

fst-john · 2026-02-24T20:34:26Z

Adds a new @Required annotation to the model package for use in marking attributes in model classes as "required". This is so we can annotate attributes of our model classes that are expected to be present on every instance of the object, so developers can safely access without any explicit null checks. Meant to be a drop-in replacement for in-line code comments or javadocs that state the same (but apply no actual enforcement at runtime)

Category (place an `x` in each of the `[ ]`)

bolt (Bolt for Java)
bolt-{sub modules} (Bolt for Java - optional modules)
slack-api-client (Slack API Clients)
slack-api-model (Slack API Data Models)
slack-api-*-kotlin-extension (Kotlin Extensions for Slack API Clients)
slack-app-backend (The primitive layer of Bolt for Java)

Requirements

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vegeris · 2026-02-24T21:02:57Z

Looks like this has been a requested feature for GSON for some time now

fst-john · 2026-02-24T21:46:35Z

Looks like this has been a requested feature for GSON for some time now

Oh yeah nice! Really the only thing I added in this implementation was to allow folks to define their own predicate that should be applied against the field that the annotation was added on. This was mainly so that folks could handle primitive types (if they wanted) since these get boxed automatically by the JVM. We could make it "dumber" though and do something similar to the stack overflow link where primitives are checked against their JVM defaults, that kinda thing 🤷‍♂️

codecov · 2026-02-25T15:52:32Z

Codecov Report

❌ Patch coverage is 58.00000% with 21 lines in your changes missing coverage. Please review.
✅ Project coverage is 73.27%. Comparing base (797d1c1) to head (df4cda2).

Files with missing lines	Patch %	Lines
...om/slack/api/util/json/RequiredAdapterFactory.java	56.41%	15 Missing and 2 partials ⚠️
...main/java/com/slack/api/util/json/GsonFactory.java	71.42%	1 Missing and 1 partial ⚠️
...lient/src/main/java/com/slack/api/SlackConfig.java	50.00%	1 Missing ⚠️
.../api/model/annotation/IsNotNullFieldPredicate.java	50.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #1558      +/-   ##
============================================
- Coverage     73.28%   73.27%   -0.02%     
- Complexity     4513     4524      +11     
============================================
  Files           477      479       +2     
  Lines         14274    14321      +47     
  Branches       1487     1494       +7     
============================================
+ Hits          10461    10494      +33     
- Misses         2922     2932      +10     
- Partials        891      895       +4

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WilliamBergamin

Nice work!! 💯 I think the approach is good 🚀

I left mainly minor comments regarding adhering to existing patterns in the project, creating a new directory for the annotations and improving test coverage

Thanks for putting this together

slack-api-model/src/test/java/test_locally/unit/GsonFactory.java

slack-api-client/src/main/java/com/slack/api/util/json/GsonFactory.java

slack-api-client/src/main/java/com/slack/api/SlackConfig.java

WilliamBergamin · 2026-02-25T17:30:29Z

slack-api-model/src/main/java/com/slack/api/model/annotation/FieldPredicate.java

@@ -0,0 +1,5 @@
+package com.slack.api.model.annotation;


I'm thinking we move this to a new package/directory

/** * Provides JSON custom annotation utilities for the classes in this library. */ package com.slack.api.util.annotations;

Given that these predicates are meant to live on slack model objects I think it makes sense for it to live in the model package, but I'm open to a new sub-module under model; maybe predicates (or something?)

...api-model/src/main/java/com/slack/api/util/json/RequiredPropertyDetectionAdapterFactory.java

slack-api-model/src/test/java/test_locally/util/JSONUtilityTest.java

WilliamBergamin · 2026-02-25T18:08:41Z

slack-api-model/src/main/java/com/slack/api/model/annotation/FieldPredicate.java

+package com.slack.api.model.annotation;
+
+public interface FieldPredicate {
+    boolean test(Object obj);


Nice job on the interface approach 🚀 but I think the test terminology might be confusing, what do you think of check or validate instead?

Maybe validate is better since it aligns with validator

Yeah that's fair; I went with test because that's the abstract method on the Predicate functional interface https://docs.oracle.com/javase/8/docs/api/java/util/function/Predicate.html

slack-api-model/src/test/java/test_locally/util/JSONUtilityTest.java

slack-api-model/src/main/java/com/slack/api/util/json/RequiredAdapterFactory.java

fst-john · 2026-02-25T22:05:17Z

slack-api-client/src/main/java/com/slack/api/util/json/GsonFactory.java

+        registerTypeAdapters(builder, failOnUnknownProps);
    }

    public static void registerTypeAdapters(GsonBuilder builder, boolean failOnUnknownProps) {


I don't know why this is public but I don't wanna break anybody, so leaving it as is 🤷‍♂️

WilliamBergamin

Looking good 💯 thanks for addressing my comments

Left 2 more comments! let mw know what you think

The one on the test GsonFactory is a nice to have and aims to maintain existing pattern in the project

slack-api-client/src/main/java/com/slack/api/util/json/GsonFactory.java

slack-api-model/src/test/java/test_locally/unit/GsonFactory.java

fst-john · 2026-02-26T16:02:09Z

slack-api-client/src/main/java/com/slack/api/util/json/GsonFactory.java

        registerTypeAdapters(gsonBuilder, failOnUnknownProps);
+
        if (failOnUnknownProps || config.isLibraryMaintainerMode()) {
-            gsonBuilder = gsonBuilder.registerTypeAdapterFactory(new UnknownPropertyDetectionAdapterFactory());


This reassignment is redundant, so removing it

fst-john · 2026-02-26T16:02:32Z

slack-api-client/src/main/java/com/slack/api/util/json/GsonFactory.java

+            gsonBuilder.registerTypeAdapterFactory(new RequiredPropertyDetectionAdapterFactory());
        }
        if (config.isPrettyResponseLoggingEnabled()) {
-            gsonBuilder = gsonBuilder.setPrettyPrinting();


Same thing here - there's no need for the re-assignmen

WilliamBergamin

Nice thanks for working on this 🚀 And your patients with the feedback 🙏

fst-john added 4 commits February 23, 2026 17:47

impl

b6fc327

update javadocs

61394ab

updates

00d45fa

update javadocs

ead8247

fst-john requested a review from a team as a code owner February 24, 2026 20:34

salesforce-cla bot added the cla:signed label Feb 24, 2026

fst-john added 2 commits February 24, 2026 15:39

small update

f04be39

add a couple more test cases

8e21407

cache FieldPredicate instances upfront

df4cda2

WilliamBergamin requested changes Feb 25, 2026

View reviewed changes

fst-john added 2 commits February 25, 2026 16:54

address comments

f40b893

oops

d4ca333

fst-john requested a review from WilliamBergamin February 25, 2026 22:00

fst-john commented Feb 25, 2026

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WilliamBergamin reviewed Feb 26, 2026

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slack-api-client/src/main/java/com/slack/api/util/json/GsonFactory.java Outdated Show resolved Hide resolved

slack-api-model/src/test/java/test_locally/unit/GsonFactory.java Outdated Show resolved Hide resolved

addressing more comments

4339fc2

fst-john commented Feb 26, 2026

View reviewed changes

update

60de10b

fst-john requested a review from WilliamBergamin February 26, 2026 16:04

WilliamBergamin approved these changes Feb 26, 2026

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move packages and use java8 compliant syntax

e8ca214

fst-john requested a review from WilliamBergamin February 26, 2026 20:29

WilliamBergamin approved these changes Feb 26, 2026

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WilliamBergamin enabled auto-merge (squash) February 26, 2026 21:46

WilliamBergamin disabled auto-merge February 26, 2026 21:56

WilliamBergamin merged commit 372fff8 into slackapi:main Feb 26, 2026
5 of 12 checks passed

fst-john deleted the fstj_add_required_annotation branch February 26, 2026 22:31

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fst-john commented Feb 24, 2026 •

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