Ensure default media type order is preserved using LinkedHashSet in mergeArrays. Fixes #2671

springdoc-openapi-starter-common/src/main/java/org/springdoc/core/models/MethodAttributes.java

@@ -26,8 +26,8 @@
 
 import java.lang.reflect.Method;
 import java.util.Arrays;
-import java.util.HashSet;
 import java.util.LinkedHashMap;
+import java.util.LinkedHashSet;
 import java.util.Locale;
 import java.util.Map;
 import java.util.Set;
@@ -306,10 +306,10 @@ private void fillMethods(String[] produces, String[] consumes, String[] headers)
 	 * @return the string [ ]
 	 */
     private String[] mergeArrays(@Nullable String[] array1, String[] array2) {
-        Set<String> uniqueValues = array1 == null ? new HashSet<>() : Arrays.stream(array1).collect(Collectors.toSet());
-        uniqueValues.addAll(Arrays.asList(array2));
-        return uniqueValues.toArray(new String[0]);
-    }
+		Set<String> uniqueValues = array1 == null ? new LinkedHashSet<>() : Arrays.stream(array1).collect(Collectors.toCollection(LinkedHashSet::new));
+		uniqueValues.addAll(Arrays.asList(array2));
+		return uniqueValues.toArray(new String[0]);
+	}
 
 	/**
 	 * Is method overloaded boolean.

springdoc-openapi-starter-common/src/test/java/org/springdoc/core/model/MethodAttributesTest.java

@@ -0,0 +1,70 @@
+package org.springdoc.core.model;
+
+import org.junit.jupiter.api.Test;
+import org.springdoc.core.models.MethodAttributes;
+
+import java.lang.reflect.Method;
+import java.util.Locale;
+
+import static org.junit.jupiter.api.Assertions.assertArrayEquals;
+
+public class MethodAttributesTest {
+
+    @Test
+    public void testMergeArrays() throws Exception {
+        MethodAttributes methodAttributes = new MethodAttributes("application/json", "application/xml", Locale.ENGLISH);
+
+        String[] array1 = {"application/json", "application/xml"};
+        String[] array2 = {"application/xml", "application/yaml"};
+
+        String[] expected = {"application/json", "application/xml", "application/yaml"};
+
+        Method mergeArraysMethod = MethodAttributes.class.getDeclaredMethod("mergeArrays", String[].class, String[].class);
+        mergeArraysMethod.setAccessible(true);
+        String[] result = (String[]) mergeArraysMethod.invoke(methodAttributes, (Object) array1, (Object) array2);
+
+        assertArrayEquals(expected, result);
+    }
+
+    @Test
+    public void testMergeArraysWithNullArray1() throws Exception {
+        MethodAttributes methodAttributes = new MethodAttributes("application/json", "application/xml", Locale.ENGLISH);
+
+        String[] array1 = null;
+        String[] array2 = {"application/xml", "application/yaml"};
+
+        String[] expected = {"application/xml", "application/yaml"};
+
+        Method mergeArraysMethod = MethodAttributes.class.getDeclaredMethod("mergeArrays", String[].class, String[].class);
+        mergeArraysMethod.setAccessible(true);
+        String[] result = (String[]) mergeArraysMethod.invoke(methodAttributes, (Object) array1, (Object) array2);
+
+        assertArrayEquals(expected, result);
+    }
+
+    @Test
+    public void testDefaultProducesMediaType() {
+        MethodAttributes methodAttributes = new MethodAttributes("application/json", "application/xml", Locale.ENGLISH);
+
+        Method method = this.getClass().getDeclaredMethods()[0];
+        methodAttributes.calculateConsumesProduces(method);
+
+        String[] expectedProduces = {"application/xml"};
+        String[] resultProduces = methodAttributes.getMethodProduces();
+
+        assertArrayEquals(expectedProduces, resultProduces);
+    }
+
+    @Test
+    public void testDefaultConsumesMediaType() {
+        MethodAttributes methodAttributes = new MethodAttributes("application/json", "application/xml", Locale.ENGLISH);
+
+        Method method = this.getClass().getDeclaredMethods()[0];
+        methodAttributes.calculateConsumesProduces(method);
+
+        String[] expectedConsumes = {"application/json"};
+        String[] resultConsumes = methodAttributes.getMethodConsumes();
+
+        assertArrayEquals(expectedConsumes, resultConsumes);
+    }
+}