Selecting users with products and names starting with 'A'

The task is to select from the list only those users who have at least one product and whose last name (or first name) starts with the letter "A" regardless of case. Each user has a field 'products' — an array/list of items, which can be empty or null. You need to write a solution using the Stream API that correctly handles any null values and optimizes the order of checks. The output should be a list of users who meet both conditions.