## Why is this an issue?

If all the keys in a `Map` are values from a single enum, it is recommended to use an `EnumMap` as the specific implementation. An `EnumMap`, which has the advantage of knowing all possible keys in advance, is more efficient compared to other implementations, as it can use a simple array as its underlying data structure.

### Noncompliant code example

    public enum Color {
      RED, GREEN, BLUE, ORANGE;
    }

    Map<Color, String> colorMap = new HashMap<>(); // Noncompliant

### Compliant solution

    public enum Color {
      RED, GREEN, BLUE, ORANGE;
    }

    Map<Color, String> colorMap = new EnumMap<>(Color.class); // Compliant

## Resources

- A Guide to EnumMap - Baeldung