Provide a test spec that reproduces the problem described in #1087

src/test/java/com/networknt/schema/Issue1087Test.java

@@ -0,0 +1,35 @@
+package com.networknt.schema;
+
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.dataformat.yaml.YAMLMapper;
+import org.hamcrest.MatcherAssert;
+import org.hamcrest.Matchers;
+import org.junit.jupiter.api.Test;
+
+import java.io.InputStream;
+
+class Issue1087Test {
+    protected JsonSchema getJsonSchemaFromStreamContent(InputStream schemaContent) throws Exception {
+        JsonSchemaFactory factory = JsonSchemaFactory.getInstance(SpecVersion.VersionFlag.V202012);
+        YAMLMapper mapper = new YAMLMapper();
+        JsonNode node = mapper.readTree(schemaContent);
+        return factory.getSchema(node, SchemaValidatorsConfig.builder().discriminatorKeywordEnabled(true).build());
+    }
+
+    protected JsonNode getJsonNodeFromStreamContent(InputStream content) throws Exception {
+        ObjectMapper mapper = new ObjectMapper();
+        return mapper.readTree(content);
+    }
+
+    @Test
+    void shouldHandleReferencesToYaml() throws Exception {
+        String schemaPath = "/schema/issue1087.yml";
+        String dataPath = "/data/issue1087.json";
+        InputStream schemaInputStream = getClass().getResourceAsStream(schemaPath);
+        JsonSchema schema = getJsonSchemaFromStreamContent(schemaInputStream);
+        InputStream dataInputStream = getClass().getResourceAsStream(dataPath);
+        JsonNode node = getJsonNodeFromStreamContent(dataInputStream);
+        MatcherAssert.assertThat(schema.validate(node), Matchers.empty());
+    }
+}

src/test/resources/data/issue1087.json

@@ -0,0 +1,3 @@
+{
+  "kind": "A"
+}

src/test/resources/data/issue668.json

@@ -2,4 +2,4 @@
   "sub1": {},
   "sub2": {},
   "sub3": {}
-}
+}

src/test/resources/schema/issue1087.yml

@@ -0,0 +1,24 @@
+$id: resource:/schema/issue1087
+$defs:
+  TypeA:
+    type: object
+    required:
+      - kind
+    properties:
+      kind:
+        type: string
+  TypeB:
+    type: object
+    required:
+      - kind
+    properties:
+      kind:
+        type: string
+oneOf:
+  - $ref: "#/$defs/TypeA"
+  - $ref: "#/$defs/TypeB"
+discriminator:
+  propertyName: kind
+  mapping:
+    A: "#/$defs/TypeA"
+    B: "#/$defs/TypeB"