Resolves #3879

Fix @JsonUnwrapped does not copy required properties

Author: twobiers

modules/swagger-core/src/main/java/io/swagger/v3/core/jackson/ModelResolver.java

@@ -124,6 +124,7 @@ public Schema resolve(AnnotatedType annotatedType, ModelConverterContext context
 
         boolean isPrimitive = false;
         Schema model = null;
+        List<String> requiredProps = new ArrayList<>();
 
         if (annotatedType == null) {
             return null;
@@ -644,7 +645,7 @@ public Schema resolve(AnnotatedType annotatedType, ModelConverterContext context
                             .ctxAnnotations(null)
                             .jsonUnwrappedHandler(null)
                             .resolveAsRef(false);
-                        handleUnwrapped(props, context.resolve(t), uw.prefix(), uw.suffix());
+                        handleUnwrapped(props, context.resolve(t), uw.prefix(), uw.suffix(), requiredProps);
                         return null;
                     } else {
                         return new Schema();
@@ -709,6 +710,9 @@ public Schema resolve(AnnotatedType annotatedType, ModelConverterContext context
         }
         if (modelProps.size() > 0) {
             model.setProperties(modelProps);
+            for(String propName : requiredProps) {
+                addRequiredItem(model, propName);
+            }
         }
 
         /**
@@ -1021,10 +1025,14 @@ protected boolean ignore(final Annotated member, final XmlAccessorType xmlAccess
         return false;
     }
 
-    private void handleUnwrapped(List<Schema> props, Schema innerModel, String prefix, String suffix) {
+    private void handleUnwrapped(List<Schema> props, Schema innerModel, String prefix, String suffix, List<String> requiredProps) {
         if (StringUtils.isBlank(suffix) && StringUtils.isBlank(prefix)) {
             if (innerModel.getProperties() != null) {
                 props.addAll(innerModel.getProperties().values());
+                if(innerModel.getRequired() != null) {
+                    requiredProps.addAll(innerModel.getRequired());
+                }
+
             }
         } else {
             if (prefix == null) {

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

@@ -0,0 +1,36 @@
+package io.swagger.v3.core.resolving;
+
+import io.swagger.v3.core.converter.ModelConverters;
+import io.swagger.v3.core.matchers.SerializationMatchers;
+import io.swagger.v3.core.resolving.resources.JacksonUnwrappedRequiredProperty;
+import org.testng.annotations.Test;
+
+public class JacksonJsonUnwrappedTest {
+
+  @Test(description = "test the @JsonUnwrapped behaviour when required Properties")
+  public void jacksonJsonUnwrappedTest() {
+
+    SerializationMatchers
+        .assertEqualsToYaml(ModelConverters.getInstance().read(
+            JacksonUnwrappedRequiredProperty.class), "InnerTypeRequired:\n" +
+            "  required:\n" +
+            "  - name\n" +
+            "  type: object\n" +
+            "  properties:\n" +
+            "    foo:\n" +
+            "      type: integer\n" +
+            "      format: int32\n" +
+            "    name:\n" +
+            "      type: string\n" +
+            "JacksonUnwrappedRequiredProperty:\n" +
+            "  required:\n" +
+            "  - name\n" +
+            "  type: object\n" +
+            "  properties:\n" +
+                "    foo:\n" +
+                "      type: integer\n" +
+                "      format: int32\n" +
+                "    name:\n" +
+                "      type: string\n");
+    }
+}

modules/swagger-core/src/test/java/io/swagger/v3/core/resolving/resources/InnerTypeRequired.java

@@ -0,0 +1,17 @@
+package io.swagger.v3.core.resolving.resources;
+
+import io.swagger.v3.oas.annotations.media.Schema;
+
+public class InnerTypeRequired {
+    public int foo;
+    @Schema(required = true)
+    public String name;
+
+    public String getName() {
+      return name;
+    }
+
+    public void setName(String name) {
+      this.name = name;
+    }
+}

modules/swagger-core/src/test/java/io/swagger/v3/core/resolving/resources/JacksonUnwrappedRequiredProperty.java

@@ -0,0 +1,15 @@
+package io.swagger.v3.core.resolving.resources;
+
+import com.fasterxml.jackson.annotation.JsonUnwrapped;
+
+public class JacksonUnwrappedRequiredProperty {
+    @JsonUnwrapped private final InnerTypeRequired innerType;
+
+    public JacksonUnwrappedRequiredProperty(InnerTypeRequired innerType) {
+      this.innerType = innerType;
+    }
+
+    public InnerTypeRequired getInnerType() {
+      return innerType;
+    }
+}