...
Line 1: the QueryAPI reference is stored in q qapi variable for later use.
Line 3: the reference to product master table is stored in q qapi variable.
Line 5: the source() method says to query table tLine 5-8: products table with a filter expression that defines which rows to return in the result
Line 86: QueryAPI provides the result always as a stream (ResultStream interface). So it is up to you how you will consume each individual row. In our example, all rows are collected to a List.
...