Jersey Microprofile RestClient - NullPointerException when a optional FormParam is null #5254 Signed-off-by: Jorge Bescos Gascon <jorge.bescos.gascon@oracle.com>

diff --git a/ext/microprofile/mp-rest-client/src/main/java/org/glassfish/jersey/microprofile/restclient/FormParamModel.java b/ext/microprofile/mp-rest-client/src/main/java/org/glassfish/jersey/microprofile/restclient/FormParamModel.java
index a8255b9..f33b592 100644
--- a/ext/microprofile/mp-rest-client/src/main/java/org/glassfish/jersey/microprofile/restclient/FormParamModel.java
+++ b/ext/microprofile/mp-rest-client/src/main/java/org/glassfish/jersey/microprofile/restclient/FormParamModel.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2019 Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2019, 2023 Oracle and/or its affiliates. All rights reserved.
  *
  * This program and the accompanying materials are made available under the
  * terms of the Eclipse Public License v. 2.0, which is available at
@@ -45,7 +45,7 @@
                 form.param(formParamName, v.toString());
             }
         } else {
-            form.param(formParamName, resolvedValue.toString());
+            form.param(formParamName, resolvedValue == null ? null : resolvedValue.toString());
         }
         return form;
     }

diff --git a/tests/integration/microprofile/rest-client/src/test/java/org/glassfish/jersey/restclient/ApplicationResource.java b/tests/integration/microprofile/rest-client/src/test/java/org/glassfish/jersey/restclient/ApplicationResource.java
index ede06dd..a781d45 100644
--- a/tests/integration/microprofile/rest-client/src/test/java/org/glassfish/jersey/restclient/ApplicationResource.java
+++ b/tests/integration/microprofile/rest-client/src/test/java/org/glassfish/jersey/restclient/ApplicationResource.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2019, 2020 Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2019, 2023 Oracle and/or its affiliates. All rights reserved.
  *
  * This program and the accompanying materials are made available under the
  * terms of the Eclipse Public License v. 2.0, which is available at
@@ -21,6 +21,7 @@
 
 import javax.json.JsonValue;
 import javax.ws.rs.Consumes;
+import javax.ws.rs.FormParam;
 import javax.ws.rs.GET;
 import javax.ws.rs.HeaderParam;
 import javax.ws.rs.POST;
@@ -76,4 +77,10 @@
     @Path("content1/{content1}/content0/{content0: [0-9]{4}}")
     @Produces(MediaType.TEXT_PLAIN)
     String regex0(@PathParam("content1") String context0, @PathParam("content0") String context1);
+
+    @POST
+    @Path("formParam")
+    @Consumes(MediaType.APPLICATION_FORM_URLENCODED)
+    @Produces(MediaType.TEXT_PLAIN)
+    String formParam(@FormParam("param") String param);
 }

diff --git a/tests/integration/microprofile/rest-client/src/test/java/org/glassfish/jersey/restclient/ApplicationResourceImpl.java b/tests/integration/microprofile/rest-client/src/test/java/org/glassfish/jersey/restclient/ApplicationResourceImpl.java
index bb58e05..d098f63 100644
--- a/tests/integration/microprofile/rest-client/src/test/java/org/glassfish/jersey/restclient/ApplicationResourceImpl.java
+++ b/tests/integration/microprofile/rest-client/src/test/java/org/glassfish/jersey/restclient/ApplicationResourceImpl.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2019, 2020 Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2019, 2023 Oracle and/or its affiliates. All rights reserved.
  *
  * This program and the accompanying materials are made available under the
  * terms of the Eclipse Public License v. 2.0, which is available at
@@ -71,4 +71,9 @@
     public String regex0(String context0, String context1) {
         return context0 + "_" + context1;
     }
+
+    @Override
+    public String formParam(String param) {
+        return param;
+    }
 }

diff --git a/tests/integration/microprofile/rest-client/src/test/java/org/glassfish/jersey/restclient/RestClientModelTest.java b/tests/integration/microprofile/rest-client/src/test/java/org/glassfish/jersey/restclient/RestClientModelTest.java
index 07189c6..737d109 100644
--- a/tests/integration/microprofile/rest-client/src/test/java/org/glassfish/jersey/restclient/RestClientModelTest.java
+++ b/tests/integration/microprofile/rest-client/src/test/java/org/glassfish/jersey/restclient/RestClientModelTest.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2019, 2022 Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2019, 2023 Oracle and/or its affiliates. All rights reserved.
  *
  * This program and the accompanying materials are made available under the
  * terms of the Eclipse Public License v. 2.0, which is available at
@@ -56,4 +56,12 @@
 
         assertEquals("Hi", app.sayHi());
     }
+
+    @Test
+    public void testFormParam() throws URISyntaxException {
+        String response = RestClientBuilder.newBuilder()
+                .baseUri(new URI("http://localhost:9998"))
+                .build(ApplicationResource.class).formParam(null);
+        assertEquals("", response);
+    }
 }