Filter for Java (server) snippet

[angelozerr]

Once #251 will be merged, we need to improve Java snippets completion:

• filter Java snippets according to some conditions like:
  • if project has some dependency (ex : Open API @operation snippet should be shown only if the project have the openapi dependency)
  • where completion has been triggered (ex : Open API @operation snippet should be shown only if completion is triggered before a class, etc)

To do that, we must delegate those 2 features on JDT LS side. We could have a microprofile/java/completion/resolveCompletionContext JDT LS command which:

• resolve condition (ex have this dependency? is completion is triggered before class, etc)

The idea is when completion is opened and snippets requires condition and compute of context , it should call one time the resolveCompletionContext which should resolve condition and compute of context.

[angelozerr]

@rzgry here the idea that I have in my mind to manage filter for snippet. Takes a sample with Metrics snippet:

The idea is to write a context like this:

"context": {
    	"scope": ["method", "field", "parameter", "annotation_type"],
    	"dependency": "microprofile-metrics-api"
    }

in other words:

"@Metric": {
    "prefix": [
      "@Metric"
    ],
    "body": [
      "@Metric(",
      "\tname = \"${1:name}\",",
      "\tdescription = \"${2:description}\"",
      ")"
    ],
    "description": "An annotation that contains the metadata information when requesting a metric to be injected or produced. This annotation can be used on fields of type Meter, Timer, Counter, and Histogram. For Gauge, the @Metric annotation can only be used on producer methods/fields.",
    "context": {
    	"scope": ["method", "field", "parameter", "annotation_type"],
    	"dependency": "microprofile-metrics-api"
    }
  }

The context means

• target : the snippet is shown only when completion is triggered before a method, field, parameter or annotation_type.
• dependency : the snippet is shown only when project has the microprofile-metrics-api dependency.

@rzgry do you like this idea? Please give me feedback.

If you like it, could you create a PR with the context for mp-* snippets please. Thanks!

[rzgry]

Looks good to me. I can make a PR to add context to the existing MicroProfile snippets.