Indent with 4 spaces and add newline to end of file

exercises/sieve/src/main/java/Sieve.java

@@ -1,11 +1,11 @@
 import java.util.List;
 
 public class Sieve {
-	public Sieve(int maxPrime) {
-		throw new UnsupportedOperationException("Delete this statement and provide your own implementation.");
+    public Sieve(int maxPrime) {
+        throw new UnsupportedOperationException("Delete this statement and provide your own implementation.");
     }
 
     public List<Integer> getPrimes() {
-    	throw new UnsupportedOperationException("Delete this statement and provide your own implementation.");
+        throw new UnsupportedOperationException("Delete this statement and provide your own implementation.");
     }
-}
+}