Fix Refinements After Early Return

[rcosta358]

Description

Fixes #68.
Uses the canCompleteNormally method introduced in #210 to preserve the condition of the branch that continues after an early return.

Example

public static int divide(int a, @Refinement("b != 0") int b) {
    return a / b;
}

public static void divideUnlessZero(int x, int y) {
    if (y == 0) return;
    divide(x, y); // y != 0 on every reachable path
}

Related Issue

#68.

Type of change

• Bug fix
• New feature
• Documentation update
• Code refactoring

Checklist

• Added/updated tests under liquidjava-example/src/main/java/testSuite/ (Correct* / Error*)
• mvn test passes locally
• Updated docs/README if behavior or API changed (not applicable; no API or documentation changes)