[java] add useNullForUnknownEnumValue option (#633)

samples/server/petstore/springboot-delegate-j8/src/main/java/org/openapitools/model/EnumArrays.java

@@ -43,7 +43,7 @@ public class EnumArrays   {
           return b;
         }
       }
-      return null;
+      throw new IllegalArgumentException("Unexpected value '" + text + "'");
     }
   }
 
@@ -77,7 +77,7 @@ public class EnumArrays   {
           return b;
         }
       }
-      return null;
+      throw new IllegalArgumentException("Unexpected value '" + text + "'");
     }
   }
 

samples/server/petstore/springboot-delegate-j8/src/main/java/org/openapitools/model/EnumClass.java

@@ -37,7 +37,7 @@ public enum EnumClass {
         return b;
       }
     }
-    return null;
+    throw new IllegalArgumentException("Unexpected value '" + text + "'");
   }
 }
 

samples/server/petstore/springboot-delegate-j8/src/main/java/org/openapitools/model/EnumTest.java

@@ -44,7 +44,7 @@ public class EnumTest   {
           return b;
         }
       }
-      return null;
+      throw new IllegalArgumentException("Unexpected value '" + text + "'");
     }
   }
 
@@ -80,7 +80,7 @@ public class EnumTest   {
           return b;
         }
       }
-      return null;
+      throw new IllegalArgumentException("Unexpected value '" + text + "'");
     }
   }
 
@@ -114,7 +114,7 @@ public class EnumTest   {
           return b;
         }
       }
-      return null;
+      throw new IllegalArgumentException("Unexpected value '" + text + "'");
     }
   }
 
@@ -148,7 +148,7 @@ public class EnumTest   {
           return b;
         }
       }
-      return null;
+      throw new IllegalArgumentException("Unexpected value '" + text + "'");
     }
   }
 

samples/server/petstore/springboot-delegate-j8/src/main/java/org/openapitools/model/MapTest.java

@@ -49,7 +49,7 @@ public class MapTest   {
           return b;
         }
       }
-      return null;
+      throw new IllegalArgumentException("Unexpected value '" + text + "'");
     }
   }
 

samples/server/petstore/springboot-delegate-j8/src/main/java/org/openapitools/model/Order.java

@@ -56,7 +56,7 @@ public class Order   {
           return b;
         }
       }
-      return null;
+      throw new IllegalArgumentException("Unexpected value '" + text + "'");
     }
   }
 

samples/server/petstore/springboot-delegate-j8/src/main/java/org/openapitools/model/OuterEnum.java

@@ -37,7 +37,7 @@ public enum OuterEnum {
         return b;
       }
     }
-    return null;
+    throw new IllegalArgumentException("Unexpected value '" + text + "'");
   }
 }
 

samples/server/petstore/springboot-delegate-j8/src/main/java/org/openapitools/model/Pet.java

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