Add non-null default parameters for disjoint pool

[vinser52]

Rationale

Today the params of the disjoint pool are initialized with nulls. We need to agree on meaningful default parameters and mention it in the documentation.

API Changes

N/A

Implementation details

Add default parameters and update documentation.

[lplewa]

duplicate of:
#804

[lukaszstolarczuk]

ref. #1377 and fixed in #1409