Java for Python developers

Prompt A. "You port a small Python helper (a function over a list of dicts) into Java for a Kafka Streams job. Walk a Python developer through your type decisions. Say what becomes a record. Say what becomes List<...> or Map<...>. Say where Optional replaces None. Say how you signal a bad input."

Prompt B. "Explain the most common bug that a Python developer hits in the first week of Java: comparing objects with ==. Say why it happens and how to fix it."

Rubric — a strong explanation hits these (5–7):

• Chooses a record for the immutable data carrier. Explains that it generates equals/hashCode/toString (dataclass analogy).
• Uses generic collections (List<T>, Map<K,V>). Says the compiler checks the element type.
• Uses Optional<T> (not null) to express "maybe absent". Shows orElse/map/ifPresent.
• Distinguishes checked from unchecked exceptions. Picks the right one for a bad argument (IllegalArgumentException, unchecked).
• Explains that == is reference identity on objects and .equals() is value equality.
• Notes that Java has no truthiness. Conditions must be boolean (!list.isEmpty()).
• (Bonus) Mentions the requirement that the package matches the directory layout.