[Java] Invalid generated code for primitive double array members

Description

Running the openapi-generator-cli.jar with --type-mappings Integer=int,Boolean=boolean,Float=float,Double=double --language-specific-primitives boolean,int,float,double options, generates incorrect private List<double> vector = null; code.

openapi-generator version

3.3.3-SNAPSHOT (30bfebfa1670840f66f667fc04924391e1994d57) / master

OpenAPI declaration file content or url

Partial content:

"Features": {
	"type": "object",
	"required": [
	  "features"
	],
	"properties": {
	  "algorithm": {
      "description": "The name and version of the algorithm used for feature extraction",
      "type": "string",
      "example": "Euclidean tripartite loss function"
	  },
	  "metric": {
      "description": "The recommended type of metric used ",
      "type": "string",
      "example": "Euclidean tripartite loss function",
      "enum": [
        "euclidean",
        "manhattan",
        "cosine"
      ]
	  },
      "threshold": {
      "description": "The value of the metric threshold",
      "type": "number",
      "format": "double",
      "example": 0.8
	  },
	  "vector": {
      "description": "N-dimensional feature vector of numerical features representing the unique signature of the object",
      "type": "array",
      "items": {
        "type": "number",
        "format": "double"
      }
	  }
	}
},

Full spec is available here: https://github.com/deepviss/deepviss-server-example/blob/master/src/main/resources/deep-viss-openapi-v3.json

Command line used for generation

java -jar openapi-generator-cli.jar generate -i https://raw.githubusercontent.com/deepviss/deepviss-server-example/master/src/main/resources/deep-viss-openapi-v3.json -l java -o ~/Downloads/generated/ --type-mappings Integer=int,Boolean=boolean,Float=float,Double=double --language-specific-primitives boolean,int,float,double

Steps to reproduce

Generate code with the above specified command.
Open ~/Downloads/generated/src/main/java/org/openapitools/client/model/Features.java and notice the following syntax error:

private List<double> vector = null;

Expected declaration type is:

private double[] vector;

Related issues/PRs

None

Suggest a fix/enhancement

Suggested fix would be to correctly interpret type-mappings and language-specific-primitives options and adjust code generation logic to output double[] instead of List<double>. The same error might reproduce (not tested) for int, float and boolean arrays.

Start by running the listed openapi-generator-cli command and inspect generated src/main/java/org/openapitools/client/model/Features.java. Verify that the vector member is emitted as double[] rather than List, and check whether the same behavior occurs for int, float, and boolean arrays.