I have a case where both the columns and rows are appending at runtime based on
the number of elements in a list. The most convenient way I have found is to
use FormLayout and its .appendRow() and .appendColumn() methods. However, there
is no empty constructor so I need to do a new FormLayout(new ColumnSpec, new
RowSpec) to trick FormLayout into starting with no definitions.
There should be an empty constructor for such cases.