[java] add useNullForUnknownEnumValue option (#633)

samples/client/petstore/java/resttemplate-withXml/src/main/java/org/openapitools/client/model/EnumArrays.java

@@ -64,7 +64,7 @@ public class EnumArrays {
           return b;
         }
       }
-      return null;
+      throw new IllegalArgumentException("Unexpected value '" + text + "'");
     }
   }
 
@@ -104,7 +104,7 @@ public class EnumArrays {
           return b;
         }
       }
-      return null;
+      throw new IllegalArgumentException("Unexpected value '" + text + "'");
     }
   }
 

samples/client/petstore/java/resttemplate-withXml/src/main/java/org/openapitools/client/model/EnumClass.java

@@ -55,7 +55,7 @@ public enum EnumClass {
         return b;
       }
     }
-    return null;
+    throw new IllegalArgumentException("Unexpected value '" + text + "'");
   }
 }
 

samples/client/petstore/java/resttemplate-withXml/src/main/java/org/openapitools/client/model/EnumTest.java

@@ -65,7 +65,7 @@ public class EnumTest {
           return b;
         }
       }
-      return null;
+      throw new IllegalArgumentException("Unexpected value '" + text + "'");
     }
   }
 
@@ -107,7 +107,7 @@ public class EnumTest {
           return b;
         }
       }
-      return null;
+      throw new IllegalArgumentException("Unexpected value '" + text + "'");
     }
   }
 
@@ -147,7 +147,7 @@ public class EnumTest {
           return b;
         }
       }
-      return null;
+      throw new IllegalArgumentException("Unexpected value '" + text + "'");
     }
   }
 
@@ -187,7 +187,7 @@ public class EnumTest {
           return b;
         }
       }
-      return null;
+      throw new IllegalArgumentException("Unexpected value '" + text + "'");
     }
   }
 

samples/client/petstore/java/resttemplate-withXml/src/main/java/org/openapitools/client/model/MapTest.java

@@ -73,7 +73,7 @@ public class MapTest {
           return b;
         }
       }
-      return null;
+      throw new IllegalArgumentException("Unexpected value '" + text + "'");
     }
   }
 

samples/client/petstore/java/resttemplate-withXml/src/main/java/org/openapitools/client/model/Order.java

@@ -85,7 +85,7 @@ public class Order {
           return b;
         }
       }
-      return null;
+      throw new IllegalArgumentException("Unexpected value '" + text + "'");
     }
   }
 

samples/client/petstore/java/resttemplate-withXml/src/main/java/org/openapitools/client/model/OuterEnum.java

@@ -55,7 +55,7 @@ public enum OuterEnum {
         return b;
       }
     }
-    return null;
+    throw new IllegalArgumentException("Unexpected value '" + text + "'");
   }
 }
 

samples/client/petstore/java/resttemplate-withXml/src/main/java/org/openapitools/client/model/Pet.java

@@ -103,7 +103,7 @@ public class Pet {
           return b;
         }
       }
-      return null;
+      throw new IllegalArgumentException("Unexpected value '" + text + "'");
     }
   }