Default YAML mapper quotes "y" as a key

[tcrespog]

Hi, after upgrading from the 2.11.4 version of the library to the 2.12.x line I've noticed that a default YAML mapper...

ObjectMapper mapper = new ObjectMapper(new YAMLFactory());

...is quoting the y character when found as a key, whereas other single character keys (or longer string keys for that matter) are not being quoted. For example, the code...

ObjectMapper defaultMapper = new ObjectMapper(new YAMLFactory());

Map<String, Integer> map = new HashMap<>();
map.put("x", 1);
map.put("y", 2);
map.put("z", 3);
defaultMapper.writeValueAsString(map);

...generates the YAML...

---
x: 1
"y": 2
z: 3

...whereas using 2.11.4 it generates:

---
x: 1
y: 2
z: 3

What is the reason behind such new behavior? Thanks.

(I've uploaded a sample repo (https://github.com/tcrespog/jackson-yml-test) with a simple test that reproduces the aforementioned behavior)

[tcrespog]

I think I've found the rationale behind this behavior in these links:

• https://github.com/FasterXML/jackson-dataformats-text/blob/2.12/yaml/src/main/java/com/fasterxml/jackson/dataformat/yaml/util/StringQuotingChecker.java#L26
• quote special boolean characters when writing #225
• Quote 'y'/'Y'/'n'/'N' as names too (to avoid problems with Boolean keys) #226
• https://yaml.org/type/bool.html

I'm closing the issue then. Sorry for the noise and thanks all the same.

[cowtowncoder]

No problem -- yes, it is a YAML oddity needed to avoid accidental coercion. Glad you found out the answer!