Fixed #2222 (Not being able to have different discriminator values map to the same entity) by switching key and value in map

modules/swagger-parser-v3/src/main/java/io/swagger/v3/parser/processors/ExternalRefProcessor.java

@@ -250,7 +250,7 @@ private void processSchema(Schema property, String file) {
                 ComposedSchema composed = (ComposedSchema) property;
                 final Map<String, String> refMap = Optional.ofNullable(composed.getDiscriminator())
                                 .map(Discriminator::getMapping).orElse(Collections.emptyMap()).entrySet()
-                                .stream().collect(Collectors.toMap(Map.Entry::getValue, Map.Entry::getKey));
+                                .stream().collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue));
                 Map<String, Schema> refCache = (!refMap.isEmpty() &&
                         (composed.getAnyOf() != null || composed.getOneOf() != null)) ? Stream.of(
                                 composed.getAnyOf(), composed.getOneOf()

modules/swagger-parser-v3/src/test/java/io/swagger/v3/parser/test/Issue2222Test.java

@@ -0,0 +1,33 @@
+package io.swagger.v3.parser.test;
+
+import io.swagger.v3.core.util.Json;
+import io.swagger.v3.oas.models.media.Discriminator;
+import io.swagger.v3.oas.models.responses.ApiResponse;
+import io.swagger.v3.parser.OpenAPIV3Parser;
+import io.swagger.v3.parser.core.models.ParseOptions;
+import io.swagger.v3.parser.core.models.SwaggerParseResult;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class Issue2222Test {
+
+    @Test
+    public void shouldMapSameEntitiesToDifferentDiscriminatorValues() {
+        ParseOptions options = new ParseOptions();
+        options.setResolveFully(true);
+        SwaggerParseResult result = new OpenAPIV3Parser().readLocation("issue-2222/openapi.yaml", null, options);
+
+        // No error/warning messages should be present, especially Duplicate key ones
+        assertEquals(0, result.getMessages().size());
+        assertEquals(1, result.getOpenAPI().getPaths().size());
+        ApiResponse response = result.getOpenAPI().getPaths().get("/mypath").readOperations().get(0).getResponses().get("200");
+        Discriminator discriminator = response.getContent().get("application/json").getSchema().getItems().getDiscriminator();
+        assertEquals("discriminatorProperty", discriminator.getPropertyName());
+        assertEquals("#/components/schemas/TypeA", discriminator.getMapping().get("ONE"));
+        assertEquals("#/components/schemas/TypeB", discriminator.getMapping().get("TWO"));
+        assertEquals("#/components/schemas/TypeB", discriminator.getMapping().get("THREE"));
+        assertEquals("#/components/schemas/TypeB", discriminator.getMapping().get("FOUR"));
+        assertEquals("#/components/schemas/TypeB", discriminator.getMapping().get("FIVE"));
+    }
+}

modules/swagger-parser-v3/src/test/java/io/swagger/v3/parser/test/OpenAPIV3RefTest.java

@@ -83,7 +83,11 @@ public void testDiscriminatorMappingRefsUpdated() {
         Set<String> allOfs = ((List<Schema>)reqSchema.getAnyOf())
                 .stream().map(Schema::get$ref).collect(Collectors.toSet());
         assertTrue(allOfs.stream().allMatch(s -> s.contains(COMPONENTS_SCHEMAS_REF)),"Schema mappings are processed");
-        assertTrue(allOfs.containsAll(discriminator),"Discriminator mappings are updated");
+        Set<String> allOfsNames = allOfs.stream()
+                .map(of -> of.split("/schemas/")[1]).collect(Collectors.toSet());
+        Collection<String> discriminatorNames = discriminator.stream().map(of -> of.split("/schemas/")[1]
+                .replace(".json","")).collect(Collectors.toSet());
+        assertTrue(allOfsNames.containsAll(discriminatorNames),"Discriminator mappings are updated");
 
     }
 

modules/swagger-parser-v3/src/test/resources/issue-2222/mypath.yaml

@@ -0,0 +1,61 @@
+  get:
+    summary: Get all objects
+    operationId: getObjects
+    responses:
+      '200':
+        description: "List of all the objects."
+        content:
+          application/json:
+            schema:
+              type: array
+              items:
+                oneOf:
+                  - $ref: '#/components/schemas/TypeA'
+                  - $ref: '#/components/schemas/TypeB'
+                discriminator:
+                  propertyName: discriminatorProperty
+                  mapping:
+                    ONE: '#/components/schemas/TypeA'
+                    TWO: '#/components/schemas/TypeB'
+                    THREE: '#/components/schemas/TypeB'
+                    FOUR: '#/components/schemas/TypeB'
+                    FIVE: '#/components/schemas/TypeB'
+
+  components:
+    schemas:
+      BaseType:
+        type: object
+        required:
+          - discriminatorProperty
+        properties:
+          discriminatorProperty:
+            type: string
+            description: A property used to determine the concrete object type.
+            enum: [ONE, TWO, THREE, FOUR, FIVE]
+          id:
+            type: string
+            description: Unique identifier for the object.
+
+      TypeA:
+        allOf:
+          - $ref: '#/components/schemas/BaseType'
+          - type: object
+            properties:
+              discriminatorProperty:
+                type: string
+                enum: [ONE]
+              name:
+                type: string
+                description: A name specific to TypeA.
+
+      TypeB:
+        allOf:
+          - $ref: '#/components/schemas/BaseType'
+          - type: object
+            properties:
+              discriminatorProperty:
+                type: string
+                enum: [TWO, THREE, FOUR, FIVE]
+              value:
+                type: number
+                description: A numeric value specific to TypeB.

modules/swagger-parser-v3/src/test/resources/issue-2222/openapi.yaml

@@ -0,0 +1,9 @@
+openapi: 3.0.0
+info:
+  title: Example API
+  version: 1.0.0
+  description: Example API demonstrating polymorphic response with external schemas.
+
+paths:
+    /mypath:
+      $ref: './mypath.yaml'