Move sample to unit test

See gh-28904

spring-core/src/test/java/org/springframework/core/GenericTypeResolverTests.java

@@ -239,6 +239,13 @@ class GenericTypeResolverTests {
 		assertThat(resolvableType.resolveGenerics()).containsExactly(Object.class);
 	}
 
+	@Test // gh-28904
+	void resolveGenericWithDifferentInterfaceOrder() {
+		Type f = First.class.getTypeParameters()[0];
+		assertThat(resolveType(f, FirstSecondService.class)).isEqualTo(Integer.class);
+		assertThat(resolveType(f, SecondFirstService.class)).isEqualTo(Integer.class);
+	}
+
 	private static Method method(Class<?> target, String methodName, Class<?>... parameterTypes) {
 		Method method = findMethod(target, methodName, parameterTypes);
 		assertThat(method).describedAs(target.getName() + "#" + methodName).isNotNull();
@@ -428,4 +435,25 @@ class GenericTypeResolverTests {
 	interface IdFixingRepository<T> extends Repository<T, Long> {
 	}
 
+	interface First<F extends Number> {
+
+		default void foo(F f) {
+			// ...
+		}
+	}
+
+	interface Second<B> {
+
+		default void bar(B b) {
+			// ...
+		}
+	}
+
+	static class FirstSecondService implements First<Integer>, Second<String> {
+	}
+
+	static class SecondFirstService implements Second<String>, First<Integer> {
+	}
+
+
 }