Binding to immutable Map fails with UnsupportedOperationException

[mbhave]

It works for Collections. See #9290

[mbhave]

Actually, maybe this is expected behavior since for collections we replace the entire collection but for Maps we merge.

[philwebb]

Feels like we should be able to do something similar to the #9290 fix.

[wilkinsona]

@bismaya123 It's difficult to offer any insight based on a single line from a stack trace, but you appear to be trying to add an entry to an immutable map. Without knowing more about that map – whether you created it or retrieved it from somewhere else – I can't say what you need to do to fix your problem. As mentioned in the guidelines for contributing, we prefer to use GitHub issues only for bugs and enhancements so please follow up on Stack Overflow or Gitter.

[bismaya123]

@wilkinsona thanks for quick response, yes it is retrieved for Spring Boot 2.3.1.
java.lang.UnsupportedOperationException: null
at java.util.Collections$UnmodifiableMap.put(Collections.java:1459).

I'm using MapPropertySource, which is internally generating an immutable map, where as in 2.0.0 its internally generating a LinkedHashMap.