[Java] Handle discriminator mapping non-ref name

The `mapping` property of the [Discriminator Object] is "An object to
hold mappings between payload values and schema names or references."
The subsequent examples in the spec have `mapping`s of both types.
The `mapping` support introduced in OpenAPITools#536 only supports references.

Update the code to support names (identified by lack of `/`) or
references and change a test mapping to cover this case.

[Discriminator Object]: https://github.com/OAI/OpenAPI-Specification/blob/master/versions/3.0.2.md#discriminatorObject

Signed-off-by: Kevin Locke <[email protected]>

Author: kevinoid

modules/openapi-generator/src/main/java/org/openapitools/codegen/DefaultCodegen.java

@@ -1860,8 +1860,10 @@ private CodegenDiscriminator createDiscriminator(String schemaName, Schema schem
         discriminator.setMapping(schema.getDiscriminator().getMapping());
         if (schema.getDiscriminator().getMapping() != null && !schema.getDiscriminator().getMapping().isEmpty()) {
             for (Entry<String, String> e : schema.getDiscriminator().getMapping().entrySet()) {
-                String name = toModelName(ModelUtils.getSimpleRef(e.getValue())); // e.g e.getValue => #/components/schemas/Dog
-                discriminator.getMappedModels().add(new MappedModel(e.getKey(), name));
+                String nameOrRef = e.getValue();
+                String name = nameOrRef.indexOf('/') >= 0 ? ModelUtils.getSimpleRef(nameOrRef) : nameOrRef;
+                String modelName = toModelName(name);
+                discriminator.getMappedModels().add(new MappedModel(e.getKey(), modelName));
             }
         } else {
             Map<String, Schema> allDefinitions = ModelUtils.getSchemas(this.openAPI);

modules/openapi-generator/src/test/java/org/openapitools/codegen/DefaultCodegenTest.java

@@ -582,7 +582,7 @@ private void verifyPersonDiscriminator(CodegenDiscriminator discriminator) {
         test.setPropertyName("DollarUnderscoretype");
         test.setMapping(new HashMap<>());
         test.getMapping().put("a", "#/components/schemas/Adult");
-        test.getMapping().put("c", "#/components/schemas/Child");
+        test.getMapping().put("c", "Child");
         test.getMappedModels().add(new CodegenDiscriminator.MappedModel("a", "Adult"));
         test.getMappedModels().add(new CodegenDiscriminator.MappedModel("c", "Child"));
         Assert.assertEquals(discriminator, test);

modules/openapi-generator/src/test/resources/3_0/allOf.yaml

@@ -32,7 +32,7 @@ components:
         propertyName: $_type
         mapping:
           a: '#/components/schemas/Adult'
-          c: '#/components/schemas/Child'
+          c: Child
       properties:
         $_type:
           type: string