There seems to be a problem with CMMN Human Activities and Embedded Forms in v7.15.0.
If I deploy and instantiate the test case [diagram_1.cmmn (1.3 KB) | form.txt (29 Bytes) 
change .txt to .html | diagram_1.bpmn (2.9 KB)] on (a fresh Camunda Platform Run) v7.15.0, the following exception is thrown:
The process definition id is mandatory, but ‘null’ has been provided.
If I run the same test case with Camunda Platform Run v7.14.0, I can confirm that the error does not occur.
I am aware that “CMMN never lived up to its potential” (I also know the blog post about this); nevertheless, I would be happy if CMMN would not getting unusable due to version incompatibility issues.