docs: remove Serializable from Route.*.postData in java (#19532)

We only support String and byte[] and throw otherwise, align the types
with it.

docs/src/api/class-route.md

@@ -114,11 +114,18 @@ If set changes the request method (e.g. GET or POST).
 
 ### option: Route.continue.postData
 * since: v1.8
-* langs: js, python, java
+* langs: js, python
 - `postData` <[string]|[Buffer]|[Serializable]>
 
 If set changes the post data of request.
 
+### option: Route.continue.postData
+* since: v1.8
+* langs: java
+- `postData` <[string]|[Buffer]>
+
+If set changes the post data of request.
+
 ### option: Route.continue.postData
 * since: v1.8
 * langs: csharp
@@ -390,11 +397,18 @@ If set changes the request method (e.g. GET or POST).
 
 ### option: Route.fallback.postData
 * since: v1.23
-* langs: js, python, java
+* langs: js, python
 - `postData` <[string]|[Buffer]|[Serializable]>
 
 If set changes the post data of request.
 
+### option: Route.fallback.postData
+* since: v1.23
+* langs: java
+- `postData` <[string]|[Buffer]>
+
+If set changes the post data of request.
+
 ### option: Route.fallback.postData
 * since: v1.23
 * langs: csharp
@@ -481,7 +495,7 @@ If set changes the request URL. New URL must have same protocol as original one.
 If set changes the request method (e.g. GET or POST).
 
 ### option: Route.fetch.postData
-* langs: js, python, java
+* langs: js, python
 * since: v1.29
 - `postData` <[string]|[Buffer]|[Serializable]>
 
@@ -489,6 +503,13 @@ Allows to set post data of the request. If the data parameter is an object, it w
 and `content-type` header will be set to `application/json` if not explicitly set. Otherwise the `content-type` header will be
 set to `application/octet-stream` if not explicitly set.
 
+### option: Route.fetch.postData
+* langs: java
+* since: v1.29
+- `postData` <[string]|[Buffer]>
+
+If set changes the post data of request.
+
 ### option: Route.fetch.postData
 * since: v1.29
 * langs: csharp