When serializing a POJO the properties are identified by** getter methods, *setter methods and* fields. (see http://mongodb.github.io/mongo-java-driver/3.6/bson/pojos/)

If the POJO impl. contains non standard getter e.g.

public class SomeClass {

private String someField1;

private String someField2;

 

public String getSomeField1(){

  return someField1;

}

 

public String getSomeField2(){

  return someField2;

}

 

public Integer getCalculation(){
  // return some calculated value

}

}

a property "calculation" with some value will be serialized which is not intendet. Sure, you can use some @BsonIgnore annotation to avoid that but you have to check the serialization bahaviour every time the POJO is extended by some get*() method. 

Another issue is when integrating a given POJO with large amount of such non-standard get*() methods.

It would be a great benefit to register some Convention which says: "serialize only the fields and ignore getter methods".