Recipe to convert collection literals which are never mutated to constants

What problem are you trying to solve?

Performance and readability. Avoid constructing the collection objects too many times.

What precondition(s) should be checked before applying this recipe?

There's a collection literal (or alike) which:

• is not returned beyond the current scope
• has no mutations of the content

Describe the situation before applying the recipe

public boolean isWeekend(String day) {
    return Set.of("Saturday", "Sunday").contains(day);
}

Describe the situation after applying the recipe

private static final Set<String> WEEKEND_DAYS = Set.of("Saturday", "Sunday");

public boolean isWeekend(String day) {
    return WEEKEND_DAYS.contains(day);
}

Any additional context

Probably the hardest here is the naming. But even if the name is automatically generated using org.openrewrite.java.VariableNameUtils#generateVariableName() it would still make sense.

Start by reviewing the repository's existing recipe implementations and the preconditions described here. Define how non-mutated collection literals are identified and how generated constant names should work. Done means the recipe safely handles the stated scope and mutation constraints, with coverage for the example transformation.