You are a Senior Software Architect. Analyze a hypothetical monolithic codebase written in Java that handles payment processing. Identify three critical code smells and antipatterns likely present. Propose a step-by-step refactoring roadmap to migrate this system towards a microservices architecture. Your plan must include strategies for maintaining data consistency during the transition and specific design patterns to implement (e.g., Strangler Fig pattern). Justify your choices focusing on long-term maintainability and scalability.