Description:
The Join design pattern allows multiple concurrent processes or threads to be synchronized such that they all must complete before any subsequent tasks can proceed. This pattern is particularly useful in scenarios where tasks can be executed in parallel but the subsequent tasks must wait for the completion of these parallel tasks.

Main Elements of Join Pattern:

1. Task Execution: Multiple tasks are executed concurrently.
2. Synchronization Point: A join point where all tasks must converge and synchronize.
3. Completion Handling: After all tasks reach the join point, subsequent tasks can proceed.

References:

• Join pattern on Wikipedia

Acceptance Criteria:

1. Implement a JoinPattern class demonstrating the synchronization of multiple threads using the join pattern.
2. Include a comprehensive unit test that validates the correct synchronization and execution order of threads.
3. Ensure the implementation follows the project contribution guidelines as outlined in the wiki.