Support for an empty PropertyPath [DATACMNS-1204]

[spring-projects-issues]

Jens Schauder opened DATACMNS-1204 and commented

PropertyPath.from currently doesn't allow empty (or null) source argument.

In SD JDBC this forces this lead to various places where I have to use a null to denote the root object of an Aggregate Root. It would be much nicer to allow an empty source for this. Kind of like "." or "/" in directory paths

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Referenced from: commits spring-projects/spring-data-relational@207b51b, spring-projects/spring-data-relational@207278c, spring-projects/spring-data-relational@6e89626

[mp911de]

The underlying problem is that PropertyPaths are not intended for navigating towards the root bur inside a domain type and its properties. The code on the calling side should be aware how to address the root type or whether properties inside of the type are the target for a particular operation.