Add CONTRIBUTING.md and pull request template (#429)

This should make adding new APIs clearer

.github/pull_request_template.md

@@ -0,0 +1,12 @@
+Thanks for submitting a pull request! Please check CONTRIBUTING.md for style guidelines.
+
+### Changes
+Describe your changes here
+
+### New API Checklist
+See CONTRIBUTING.md for more info.
+
+1. [ ] Documentation for every variable
+2. [ ] Class-level documentation
+3. [ ] POJO JSON parsing tests
+4. [ ] Service integration tests

CONTRIBUTING.md

@@ -0,0 +1,27 @@
+# How to Contribute
+
+## How to Add a New API
+
+### Add POJOs to API library
+I usually have ChatGPT write them for me by copying and pasting from teh OpenAI API reference ([example chat](https://chat.openai.com/share/af48ef11-0354-40b2-a8e2-3bf8e93a94a3)), but double check everything because Chat always makes mistakes, especially around adding `@JsonProperty` annotations.
+
+- Make all java variables camel case, and use `@JsonProperty` for fields that OpenAI returns as snake case
+- Include comments for each variable, I take these directly from the OpenAI website
+- Include `@Data` on every response class, and `@Builder @NoArgsConstructor @AllArgsConstructor @Data` on every request
+- Include basic class-level documentation and a link to the OpenAI reference page, [example](api/src/main/java/com/theokanning/openai/threads/Thread.java)
+- Add a JSON test for every new java object, this ensures that your definition and variable name overrides are correct.
+  - Copy the sample response from OpenAI into an api test [fixture](api/src/test/resources/fixtures)
+  - Add any missing fields to the JSON file (OpenAI doesn't always include everything)
+  - Add the class name to the test cases here [JSON test](api/src/test/java/com/theokanning/openai/JsonTest.java)
+
+### Add to [OpenAiApi](client/src/main/java/com/theokanning/openai/client/OpenAiApi.java)
+This is usually straightforward, use [OpenAiResponse](api/src/main/java/com/theokanning/openai/OpenAiResponse.java) for endpoints that return lists.
+
+### Add to [OpenAiService](service/src/main/java/com/theokanning/openai/OpenAiService.java)
+
+### Add an Integration Test
+Since 99% of the work of this library is done on OpenAI's servers, the objective of these tests is to call each endpoint at least once.  
+Specify every available parameter to make sure that OpenAI accepts everything, but don't create extra test cases unless a parameter drastically affects the results.  
+For example, [CompletionTest](service/src/test/java/com/theokanning/openai/service/CompletionTest.java) has one test for normal completions, and one for streaming.
+
+If your test relies on creating and retrieving external resources, [FineTuningTest](service/src/test/java/com/theokanning/openai/service/FineTuningTest.java) is a good example of how to share resources between tests and clean up afterwards.

README.md

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 ![Maven Central](https://img.shields.io/maven-central/v/com.theokanning.openai-gpt3-java/client?color=blue)
 
-> ⚠️ Please switch to using the new 'service' library if you need to use OpenAiService. The old 'client' OpenAiService is deprecated as of 0.10.0.  
 > ⚠️OpenAI has deprecated all Engine-based APIs. See [Deprecated Endpoints](https://github.com/TheoKanning/openai-java#deprecated-endpoints) below for more info.
 
 # OpenAI-Java
@@ -24,6 +23,7 @@ as well as an example project using the service.
 - [Fine-tuning](https://platform.openai.com/docs/api-reference/fine-tuning)
 - [Images](https://platform.openai.com/docs/api-reference/images)
 - [Moderations](https://platform.openai.com/docs/api-reference/moderations)
+- [Assistants](https://platform.openai.com/docs/api-reference/assistants)
 
 #### Deprecated by OpenAI
 - [Engines](https://platform.openai.com/docs/api-reference/engines)