add unittest for v3.1 which has both ref and description

modules/swagger-core/src/test/java/io/swagger/v3/core/resolving/v31/Ticket3900Test.java

@@ -0,0 +1,49 @@
+package io.swagger.v3.core.resolving.v31;
+
+import io.swagger.v3.core.converter.AnnotatedType;
+import io.swagger.v3.core.converter.ModelConverterContextImpl;
+import io.swagger.v3.core.jackson.ModelResolver;
+import io.swagger.v3.core.matchers.SerializationMatchers;
+import io.swagger.v3.core.resolving.SwaggerTestBase;
+import org.testng.annotations.Test;
+
+public class Ticket3900Test extends SwaggerTestBase {
+
+    @Test
+    public void testArraySchemaItemsValidation() {
+        final ModelResolver modelResolver = new ModelResolver(mapper()).openapi31(true);
+        final ModelConverterContextImpl context = new ModelConverterContextImpl(modelResolver);
+        io.swagger.v3.oas.models.media.Schema model = context.resolve(new AnnotatedType(Route.class));
+        SerializationMatchers.assertEqualsToYaml31(model, "type: object\n" +
+                "properties:\n" +
+                "  startPoint:\n" +
+                "    $ref: '#/components/schemas/GeoPoint'\n" +
+                "    description: Point where the route begins\n" +
+                "  intermediatePoint:\n" +
+                "    $ref: '#/components/schemas/GeoPoint'\n" +
+                "    description: Intermediate point of the route\n" +
+                "  endPoint:\n" +
+                "    $ref: '#/components/schemas/GeoPoint'\n" +
+                "    description: Point where the route ends");
+    }
+
+    private static class GeoPoint {
+
+        @io.swagger.v3.oas.annotations.media.Schema(description = "Longitude of geo point ( -180, 180 >")
+        public double lon;
+
+        @io.swagger.v3.oas.annotations.media.Schema(description = "Latitude of geo point < -90, 90 >")
+        public double lat;
+    }
+
+    private static class Route {
+        @io.swagger.v3.oas.annotations.media.Schema(description = "Point where the route begins")
+        public GeoPoint startPoint;
+
+        @io.swagger.v3.oas.annotations.media.Schema(description = "Intermediate point of the route")
+        public GeoPoint intermediatePoint;
+
+        @io.swagger.v3.oas.annotations.media.Schema(description = "Point where the route ends")
+        public GeoPoint endPoint;
+    }
+}