Allow handling of single-arg constructor as property based by default

class Foo {
    private final Bar bar;

    Foo(Bar bar) {
        this.bar = bar;
    }
}

With the parameter-names-module enabled I’d expect this class to be correctly deserialized from {"bar":{...}}. More than once have users hit this issue and asked why isn’t it handled this way (#1135, #8, #21). It might also be a good idea to provide an option to change this behavior (HANDLE_SINGLE_ARG_CONSTRUCTOR_AS_PROPERTY_CREATOR).

[lpandzic]

To anyone that can’t upgrade jackson you might want to try this module - https://github.com/infobip/infobip-jackson-extension#SingleArgumentPropertyCreatorAnnotationlessSupport. It might even work for some cases where ConstructorDetector.USE_PROPERTIES_BASED doesn’t work as it works differently:

• it doesn’t change default creator logic which might be wanted in some cases
• it handles only cases where there’s only one constructor and that has 1 parameter that matches 1 field for name and type
• for all other cases it backs off and lets jackson do the default behavior.

Here’s a test that probably speaks better for itself what is supported - https://github.com/infobip/infobip-jackson-extension/blob/master/infobip-jackson-extension-module/src/test/java/com/infobip/jackson/SingleArgumentPropertiesCreatorModeAnnotationIntrospectorTest.java.

[cowtowncoder]

Work here progressing, and now the original case passes when mapper is constructed like so:

ObjectMapper mapper = JsonMapper.builder()
        .constructorDetector(ConstructorDetector.USE_PROPERTIES_BASED)
        // add modules, configure etc
        .build();

I realized that implementing ConstructorSelector for selecting across multiple alternatives would get quite complicated so will for now leave only 3 configurable pieces:

1. SingleArgConstructor, the most relevant here (choice of SingleArgConstructor.PROPERTIES)
2. requireCtorAnnotation: Whether to always require annotation (@JsonCreator) or not (for those who want more not less explicit) (default: false)
3. allowJDKTypeCtors: Even if implicit discovery allowed in general, is it allowed for JDK types (java.*, javax.)? (default: false)

Of these I implemented the bigger piece (1) and need to add (2) and (3).