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OptionalMapStr, often written as OptionalMapString or OptionalMapStr, refers to a programming construct that represents a map from strings to strings that may or may not be present. It is used to distinguish between a missing map and an empty map. As a wrapper, it encodes optionality explicitly in types, reducing nil dereferences and clarifying intent in configuration, parsing, or data interchange code.

In typical usage, the optional map consists of an internal flag indicating presence and the actual map when present. Common operations include checking presence (IsPresent or HasValue), retrieving a value with a safe lookup (Get with two return values in many languages), setting a value (Set), removing a key (Delete), and clearing the map. Serialization support is often provided to marshal to and from JSON or YAML, ensuring that a missing map can remain omitted in serialized output while an empty map is serialized as {} when present.

Advantages include explicit handling of optionality, clearer error handling, and simpler APIs for components that must handle absent configuration gracefully. Potential drawbacks include added boilerplate and the need to decide zero-value semantics to avoid ambiguity between unset and empty states.

Common use cases include configuration parsing, API payload modeling, and feature-flag maps where a caller must distinguish between not providing a map and providing an empty one. The exact name and API vary by language and codebase, but the pattern remains a practical tool for robust data modeling.