Don't output intermediate aliases

export interface Parent {
  a: A;
}
export type A = RealA;

export type RealA = { realA: string };

./node_modules/.bin/ts-json-schema-generator \
    --path 'test.ts' \
    --type 'Parent' \
    --expose 'export' \
    --jsDoc 'extended'

outputs

{
  "$ref": "#/definitions/Parent",
  "$schema": "http://json-schema.org/draft-06/schema#",
  "definitions": {
    "A": {
      "$ref": "#/definitions/RealA"
    },
    "Parent": {
      "additionalProperties": false,
      "properties": {
        "a": {
          "$ref": "#/definitions/A"
        }
      },
      "required": [
        "a"
      ],
      "type": "object"
    },
    "RealA": {
      "additionalProperties": false,
      "properties": {
        "realA": {
          "type": "string"
        }
      },
      "required": [
        "realA"
      ],
      "type": "object"
    }
  }
}

However, if RealA is not referred elsewhere, it’s better to output:

{
  "$ref": "#/definitions/Parent",
  "$schema": "http://json-schema.org/draft-06/schema#",
  "definitions": {
    "A": {
      "additionalProperties": false,
      "properties": {
        "realA": {
          "type": "string"
        }
      },
      "required": [
        "realA"
      ],
      "type": "object"
    },
    "Parent": {
      "additionalProperties": false,
      "properties": {
        "a": {
          "$ref": "#/definitions/A"
        }
      },
      "required": [
        "a"
      ],
      "type": "object"
    }
    
  }
}

[domoritz]

So the idea is to never output something of the form

"XXXX": {
 "$ref": "#/definitions/YYYY"
}

and replace all occurrences of XXXX with YYYY

[kanitw]

Note that this is quite important to make the schema legible. (It will reduce number of stacks in JSON schema validation error.)