schema package with ValueType classes not documented

I just wrote a plugin function of type GroupExpandingSeriesFunctionType which returns a tiny list of sublists in each cell. I arranged the data in this hierarchy to get a better structure. Defininig the corresponding return type was a bit hard.

These are my findings:

1. The java package datameer.dap.sdk.schema is not documented in the javadoc, e.g. ValueType is missing. Workaround: IDE can peek into the classes within the jar archives.

2. There is a value type for lists in datameer.dap.sdk.schema.ListType, but how to define the type of the elements in that list? Workaround: I used another plugin to retrieve the JSON definition of the value type (list of sublists with float values) from a manually constructed column and then deserialized this JSON string in the real plugin.

 2. ValueType does not contain a static member for the list type similar to ValueType.STRING, ValueType.INTEGER, ValueType.BOOLEAN, etc.. This may be normal, as a list requires an additional element type, but then I would expect a method that creates a list value type object for a specific element type.