[java] add useNullForUnknownEnumValue option (#633)

samples/client/petstore/java/jersey2-java8/src/main/java/org/openapitools/client/model/EnumArrays.java

@@ -59,7 +59,7 @@ public class EnumArrays {
           return b;
         }
       }
-      return null;
+      throw new IllegalArgumentException("Unexpected value '" + text + "'");
     }
   }
 
@@ -97,7 +97,7 @@ public class EnumArrays {
           return b;
         }
       }
-      return null;
+      throw new IllegalArgumentException("Unexpected value '" + text + "'");
     }
   }
 

samples/client/petstore/java/jersey2-java8/src/main/java/org/openapitools/client/model/EnumClass.java

@@ -53,7 +53,7 @@ public enum EnumClass {
         return b;
       }
     }
-    return null;
+    throw new IllegalArgumentException("Unexpected value '" + text + "'");
   }
 }
 

samples/client/petstore/java/jersey2-java8/src/main/java/org/openapitools/client/model/EnumTest.java

@@ -60,7 +60,7 @@ public class EnumTest {
           return b;
         }
       }
-      return null;
+      throw new IllegalArgumentException("Unexpected value '" + text + "'");
     }
   }
 
@@ -100,7 +100,7 @@ public class EnumTest {
           return b;
         }
       }
-      return null;
+      throw new IllegalArgumentException("Unexpected value '" + text + "'");
     }
   }
 
@@ -138,7 +138,7 @@ public class EnumTest {
           return b;
         }
       }
-      return null;
+      throw new IllegalArgumentException("Unexpected value '" + text + "'");
     }
   }
 
@@ -176,7 +176,7 @@ public class EnumTest {
           return b;
         }
       }
-      return null;
+      throw new IllegalArgumentException("Unexpected value '" + text + "'");
     }
   }
 

samples/client/petstore/java/jersey2-java8/src/main/java/org/openapitools/client/model/MapTest.java

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

samples/client/petstore/java/jersey2-java8/src/main/java/org/openapitools/client/model/Order.java

@@ -72,7 +72,7 @@ public class Order {
           return b;
         }
       }
-      return null;
+      throw new IllegalArgumentException("Unexpected value '" + text + "'");
     }
   }
 

samples/client/petstore/java/jersey2-java8/src/main/java/org/openapitools/client/model/OuterEnum.java

@@ -53,7 +53,7 @@ public enum OuterEnum {
         return b;
       }
     }
-    return null;
+    throw new IllegalArgumentException("Unexpected value '" + text + "'");
   }
 }
 

samples/client/petstore/java/jersey2-java8/src/main/java/org/openapitools/client/model/Pet.java

@@ -78,7 +78,7 @@ public class Pet {
           return b;
         }
       }
-      return null;
+      throw new IllegalArgumentException("Unexpected value '" + text + "'");
     }
   }