diff --git a/pom.xml b/pom.xml
index aed340674..1bc531e44 100644
--- a/pom.xml
+++ b/pom.xml
@@ -62,7 +62,7 @@
 		<maven-release-plugin.version>3.3.1</maven-release-plugin.version>
 		<central-publishing-maven-plugin.version>0.11.0</central-publishing-maven-plugin.version>
 		<flatten-maven-plugin.version>1.8.0</flatten-maven-plugin.version>
-		<swagger-core.version>4.0.3</swagger-core.version>
+		<swagger-core.version>4.0.5</swagger-core.version>
 		<swagger-ui.version>5.32.14</swagger-ui.version>
 		<gmavenplus-plugin.version>5.1.0</gmavenplus-plugin.version>
 		<jjwt.version>0.13.0</jjwt.version>
diff --git a/springdoc-openapi-starter-webmvc-api/src/test/java/test/org/springdoc/api/v31/app115/JavaTimeOperationCustomizer.java b/springdoc-openapi-starter-webmvc-api/src/test/java/test/org/springdoc/api/v31/app115/JavaTimeOperationCustomizer.java
index 32e9be4e5..fbda7223d 100644
--- a/springdoc-openapi-starter-webmvc-api/src/test/java/test/org/springdoc/api/v31/app115/JavaTimeOperationCustomizer.java
+++ b/springdoc-openapi-starter-webmvc-api/src/test/java/test/org/springdoc/api/v31/app115/JavaTimeOperationCustomizer.java
@@ -26,7 +26,6 @@
 
 import java.time.Duration;
 import java.util.Map;
-import java.util.Set;
 
 import io.swagger.v3.oas.models.Operation;
 import io.swagger.v3.oas.models.media.Content;
@@ -47,8 +46,10 @@ public Operation customize(Operation operation, HandlerMethod handlerMethod) {
 				Content content = response.getContent();
 				if (content.containsKey(MediaType.APPLICATION_JSON_VALUE)) {
 					Schema schema = content.get(MediaType.APPLICATION_JSON_VALUE).getSchema();
-					schema.getProperties().clear();
-					schema.types(Set.of("string"));
+					if (schema.getProperties() != null) {
+						schema.getProperties().clear();
+					}
+					schema.setType("string");
 				}
 			}
 		}
diff --git a/springdoc-openapi-starter-webmvc-api/src/test/resources/results/3.1.0/app115.json b/springdoc-openapi-starter-webmvc-api/src/test/resources/results/3.1.0/app115.json
index f3685cb97..322ede3ed 100644
--- a/springdoc-openapi-starter-webmvc-api/src/test/resources/results/3.1.0/app115.json
+++ b/springdoc-openapi-starter-webmvc-api/src/test/resources/results/3.1.0/app115.json
@@ -24,7 +24,7 @@
               "application/json": {
                 "schema": {
                   "type": "string",
-                  "properties": {}
+                  "format": "duration"
                 }
               }
             }
diff --git a/springdoc-openapi-tests/springdoc-openapi-javadoc-tests/src/test/java/test/org/springdoc/api/v30/app115/JavaTimeOperationCustomizer.java b/springdoc-openapi-tests/springdoc-openapi-javadoc-tests/src/test/java/test/org/springdoc/api/v30/app115/JavaTimeOperationCustomizer.java
index 544878a19..5991b4f67 100644
--- a/springdoc-openapi-tests/springdoc-openapi-javadoc-tests/src/test/java/test/org/springdoc/api/v30/app115/JavaTimeOperationCustomizer.java
+++ b/springdoc-openapi-tests/springdoc-openapi-javadoc-tests/src/test/java/test/org/springdoc/api/v30/app115/JavaTimeOperationCustomizer.java
@@ -58,7 +58,9 @@ public Operation customize(Operation operation, HandlerMethod handlerMethod) {
 				Content content = response.getContent();
 				if (content.containsKey(MediaType.APPLICATION_JSON_VALUE)) {
 					Schema schema = content.get(MediaType.APPLICATION_JSON_VALUE).getSchema();
-					schema.getProperties().clear();
+					if (schema.getProperties() != null) {
+						schema.getProperties().clear();
+					}
 					schema.setType("string");
 				}
 			}
diff --git a/springdoc-openapi-tests/springdoc-openapi-javadoc-tests/src/test/java/test/org/springdoc/api/v31/app115/JavaTimeOperationCustomizer.java b/springdoc-openapi-tests/springdoc-openapi-javadoc-tests/src/test/java/test/org/springdoc/api/v31/app115/JavaTimeOperationCustomizer.java
index e891dcec7..f3f7aea5e 100644
--- a/springdoc-openapi-tests/springdoc-openapi-javadoc-tests/src/test/java/test/org/springdoc/api/v31/app115/JavaTimeOperationCustomizer.java
+++ b/springdoc-openapi-tests/springdoc-openapi-javadoc-tests/src/test/java/test/org/springdoc/api/v31/app115/JavaTimeOperationCustomizer.java
@@ -28,7 +28,6 @@
 
 import java.time.Duration;
 import java.util.Map;
-import java.util.Set;
 
 import io.swagger.v3.oas.models.Operation;
 import io.swagger.v3.oas.models.media.Content;
@@ -59,8 +58,10 @@ public Operation customize(Operation operation, HandlerMethod handlerMethod) {
 				Content content = response.getContent();
 				if (content.containsKey(MediaType.APPLICATION_JSON_VALUE)) {
 					Schema schema = content.get(MediaType.APPLICATION_JSON_VALUE).getSchema();
-					schema.types(Set.of("string"));
-					schema.getProperties().clear();
+					schema.setType("string");
+					if (schema.getProperties() != null) {
+						schema.getProperties().clear();
+					}
 				}
 			}
 		}
diff --git a/springdoc-openapi-tests/springdoc-openapi-javadoc-tests/src/test/resources/results/3.0.1/app115.json b/springdoc-openapi-tests/springdoc-openapi-javadoc-tests/src/test/resources/results/3.0.1/app115.json
index 174ff999c..cde841b58 100644
--- a/springdoc-openapi-tests/springdoc-openapi-javadoc-tests/src/test/resources/results/3.0.1/app115.json
+++ b/springdoc-openapi-tests/springdoc-openapi-javadoc-tests/src/test/resources/results/3.0.1/app115.json
@@ -32,7 +32,7 @@
               "application/json": {
                 "schema": {
                   "type": "string",
-                  "properties": {}
+                  "format": "duration"
                 }
               }
             }
diff --git a/springdoc-openapi-tests/springdoc-openapi-javadoc-tests/src/test/resources/results/3.1.0/app115.json b/springdoc-openapi-tests/springdoc-openapi-javadoc-tests/src/test/resources/results/3.1.0/app115.json
index 052562581..0dc185f8f 100644
--- a/springdoc-openapi-tests/springdoc-openapi-javadoc-tests/src/test/resources/results/3.1.0/app115.json
+++ b/springdoc-openapi-tests/springdoc-openapi-javadoc-tests/src/test/resources/results/3.1.0/app115.json
@@ -32,7 +32,7 @@
               "application/json": {
                 "schema": {
                   "type": "string",
-                  "properties": {}
+                  "format": "duration"
                 }
               }
             }