9 files changed, 39 insertions, 8 deletions

diff --git a/subprojects/logic/src/main/java/tools/refinery/logic/term/Aggregator.java b/subprojects/logic/src/main/java/tools/refinery/logic/term/Aggregator.java
index 40189ebc..d99904fd 100644
--- a/subprojects/logic/src/main/java/tools/refinery/logic/term/Aggregator.java
+++ b/subprojects/logic/src/main/java/tools/refinery/logic/term/Aggregator.java
@@ -5,6 +5,8 @@
  */
 package tools.refinery.logic.term;
 
+import org.jetbrains.annotations.NotNull;
+
 import java.util.stream.Stream;
 
 public interface Aggregator<R, T> {
@@ -12,7 +14,9 @@ public interface Aggregator<R, T> {
 
         Class<T> getInputType();
 
+        @NotNull
         R aggregateStream(Stream<T> stream);
 
+        @NotNull
         R getEmptyResult();
 }
diff --git a/subprojects/logic/src/main/java/tools/refinery/logic/term/ExtremeValueAggregator.java b/subprojects/logic/src/main/java/tools/refinery/logic/term/ExtremeValueAggregator.java
index 31c61b6a..e163bfea 100644
--- a/subprojects/logic/src/main/java/tools/refinery/logic/term/ExtremeValueAggregator.java
+++ b/subprojects/logic/src/main/java/tools/refinery/logic/term/ExtremeValueAggregator.java
@@ -5,6 +5,8 @@
  */
 package tools.refinery.logic.term;
 
+import org.jetbrains.annotations.NotNull;
+
 import java.util.Comparator;
 import java.util.Objects;
 import java.util.SortedMap;
@@ -12,14 +14,14 @@ import java.util.TreeMap;
 
 public class ExtremeValueAggregator<T> implements StatefulAggregator<T, T> {
         private final Class<T> type;
-        private final T emptyResult;
+        private final @NotNull T emptyResult;
         private final Comparator<T> comparator;
 
-        public ExtremeValueAggregator(Class<T> type, T emptyResult) {
+        public ExtremeValueAggregator(Class<T> type, @NotNull T emptyResult) {
                 this(type, emptyResult, null);
         }
 
-        public ExtremeValueAggregator(Class<T> type, T emptyResult, Comparator<T> comparator) {
+        public ExtremeValueAggregator(Class<T> type, @NotNull T emptyResult, Comparator<T> comparator) {
                 this.type = type;
                 this.emptyResult = emptyResult;
                 this.comparator = comparator;
@@ -40,6 +42,7 @@ public class ExtremeValueAggregator<T> implements StatefulAggregator<T, T> {
                 return new Aggregate();
         }
 
+        @NotNull
         @Override
         public T getEmptyResult() {
                 return emptyResult;
@@ -85,6 +88,7 @@ public class ExtremeValueAggregator<T> implements StatefulAggregator<T, T> {
                         });
                 }
 
+                @NotNull
                 @Override
                 public T getResult() {
                         return isEmpty() ? emptyResult : values.firstKey();
diff --git a/subprojects/logic/src/main/java/tools/refinery/logic/term/StatefulAggregate.java b/subprojects/logic/src/main/java/tools/refinery/logic/term/StatefulAggregate.java
index 75e7ecff..960e8c53 100644
--- a/subprojects/logic/src/main/java/tools/refinery/logic/term/StatefulAggregate.java
+++ b/subprojects/logic/src/main/java/tools/refinery/logic/term/StatefulAggregate.java
@@ -5,11 +5,14 @@
  */
 package tools.refinery.logic.term;
 
+import org.jetbrains.annotations.NotNull;
+
 public interface StatefulAggregate<R, T> {
         void add(T value);
 
         void remove(T value);
 
+        @NotNull
         R getResult();
 
         boolean isEmpty();
diff --git a/subprojects/logic/src/main/java/tools/refinery/logic/term/StatefulAggregator.java b/subprojects/logic/src/main/java/tools/refinery/logic/term/StatefulAggregator.java
index 79d32535..2b9243b7 100644
--- a/subprojects/logic/src/main/java/tools/refinery/logic/term/StatefulAggregator.java
+++ b/subprojects/logic/src/main/java/tools/refinery/logic/term/StatefulAggregator.java
@@ -5,11 +5,14 @@
  */
 package tools.refinery.logic.term;
 
+import org.jetbrains.annotations.NotNull;
+
 import java.util.stream.Stream;
 
 public interface StatefulAggregator<R, T> extends Aggregator<R, T> {
         StatefulAggregate<R, T> createEmptyAggregate();
 
+        @NotNull
         @Override
         default R aggregateStream(Stream<T> stream) {
                 var accumulator = createEmptyAggregate();
@@ -21,6 +24,7 @@ public interface StatefulAggregator<R, T> extends Aggregator<R, T> {
                 return accumulator.getResult();
         }
 
+        @NotNull
         @Override
         default R getEmptyResult() {
                 return createEmptyAggregate().getResult();
diff --git a/subprojects/logic/src/main/java/tools/refinery/logic/term/StatelessAggregator.java b/subprojects/logic/src/main/java/tools/refinery/logic/term/StatelessAggregator.java
index 37db262e..e489378b 100644
--- a/subprojects/logic/src/main/java/tools/refinery/logic/term/StatelessAggregator.java
+++ b/subprojects/logic/src/main/java/tools/refinery/logic/term/StatelessAggregator.java
@@ -5,6 +5,8 @@
  */
 package tools.refinery.logic.term;
 
+import org.jetbrains.annotations.NotNull;
+
 import java.util.stream.Stream;
 
 public interface StatelessAggregator<R, T> extends Aggregator<R, T> {
@@ -12,6 +14,7 @@ public interface StatelessAggregator<R, T> extends Aggregator<R, T> {
 
         R remove(R current, T value);
 
+        @NotNull
         @Override
         default R aggregateStream(Stream<T> stream) {
                 var accumulator = getEmptyResult();
diff --git a/subprojects/logic/src/main/java/tools/refinery/logic/term/int_/IntSumAggregator.java b/subprojects/logic/src/main/java/tools/refinery/logic/term/int_/IntSumAggregator.java
index b42038ab..d4462587 100644
--- a/subprojects/logic/src/main/java/tools/refinery/logic/term/int_/IntSumAggregator.java
+++ b/subprojects/logic/src/main/java/tools/refinery/logic/term/int_/IntSumAggregator.java
@@ -5,8 +5,11 @@
  */
 package tools.refinery.logic.term.int_;
 
+import org.jetbrains.annotations.NotNull;
 import tools.refinery.logic.term.StatelessAggregator;
 
+// Singleton implementation, since there is only one way to sum integers.
+@SuppressWarnings("squid:S6548")
 public final class IntSumAggregator implements StatelessAggregator<Integer, Integer> {
         public static final IntSumAggregator INSTANCE = new IntSumAggregator();
 
@@ -23,6 +26,7 @@ public final class IntSumAggregator implements StatelessAggregator<Integer, Inte
                 return Integer.class;
         }
 
+        @NotNull
         @Override
         public Integer getEmptyResult() {
                 return 0;
diff --git a/subprojects/logic/src/main/java/tools/refinery/logic/term/real/RealSumAggregator.java b/subprojects/logic/src/main/java/tools/refinery/logic/term/real/RealSumAggregator.java
index 4b090188..b6f79270 100644
--- a/subprojects/logic/src/main/java/tools/refinery/logic/term/real/RealSumAggregator.java
+++ b/subprojects/logic/src/main/java/tools/refinery/logic/term/real/RealSumAggregator.java
@@ -5,12 +5,15 @@
  */
 package tools.refinery.logic.term.real;
 
+import org.jetbrains.annotations.NotNull;
 import tools.refinery.logic.term.StatefulAggregate;
 import tools.refinery.logic.term.StatefulAggregator;
 
 import java.util.Map;
 import java.util.TreeMap;
 
+// Singleton implementation, since there is only one way to sum reals.
+@SuppressWarnings("squid:S6548")
 public final class RealSumAggregator implements StatefulAggregator<Double, Double> {
         public static final RealSumAggregator INSTANCE = new RealSumAggregator();
 
@@ -32,6 +35,7 @@ public final class RealSumAggregator implements StatefulAggregator<Double, Doubl
                 return new Aggregate();
         }
 
+        @NotNull
         @Override
         public Double getEmptyResult() {
                 return 0d;
@@ -63,6 +67,7 @@ public final class RealSumAggregator implements StatefulAggregator<Double, Doubl
                         });
                 }
 
+                @NotNull
                 @Override
                 public Double getResult() {
                         return values.entrySet()
diff --git a/subprojects/logic/src/main/java/tools/refinery/logic/term/uppercardinality/UpperCardinalitySumAggregator.java b/subprojects/logic/src/main/java/tools/refinery/logic/term/uppercardinality/UpperCardinalitySumAggregator.java
index 7c45e6ef..846e954b 100644
--- a/subprojects/logic/src/main/java/tools/refinery/logic/term/uppercardinality/UpperCardinalitySumAggregator.java
+++ b/subprojects/logic/src/main/java/tools/refinery/logic/term/uppercardinality/UpperCardinalitySumAggregator.java
@@ -5,10 +5,11 @@
  */
 package tools.refinery.logic.term.uppercardinality;
 
+import org.jetbrains.annotations.NotNull;
 import tools.refinery.logic.term.StatefulAggregate;
 import tools.refinery.logic.term.StatefulAggregator;
 
-// Singleton implementation, since there is only one way to aggregate upper cardinalities.
+// Singleton implementation, since there is only one way to sum upper cardinalities.
 @SuppressWarnings("squid:S6548")
 public class UpperCardinalitySumAggregator implements StatefulAggregator<UpperCardinality, UpperCardinality> {
         public static final UpperCardinalitySumAggregator INSTANCE = new UpperCardinalitySumAggregator();
@@ -46,8 +47,8 @@ public class UpperCardinalitySumAggregator implements StatefulAggregator<UpperCa
 
                 @Override
                 public void add(UpperCardinality value) {
-                        if (value instanceof FiniteUpperCardinality finiteUpperCardinality) {
-                                sumFiniteUpperBounds += finiteUpperCardinality.finiteUpperBound();
+                        if (value instanceof FiniteUpperCardinality(var finiteUpperBound)) {
+                                sumFiniteUpperBounds += finiteUpperBound;
                         } else if (value instanceof UnboundedUpperCardinality) {
                                 countUnbounded += 1;
                         } else {
@@ -57,8 +58,8 @@ public class UpperCardinalitySumAggregator implements StatefulAggregator<UpperCa
 
                 @Override
                 public void remove(UpperCardinality value) {
-                        if (value instanceof FiniteUpperCardinality finiteUpperCardinality) {
-                                sumFiniteUpperBounds -= finiteUpperCardinality.finiteUpperBound();
+                        if (value instanceof FiniteUpperCardinality(var finiteUpperBound)) {
+                                sumFiniteUpperBounds -= finiteUpperBound;
                         } else if (value instanceof UnboundedUpperCardinality) {
                                 countUnbounded -= 1;
                         } else {
@@ -66,6 +67,7 @@ public class UpperCardinalitySumAggregator implements StatefulAggregator<UpperCa
                         }
                 }
 
+                @NotNull
                 @Override
                 public UpperCardinality getResult() {
                         return countUnbounded > 0 ? UpperCardinalities.UNBOUNDED : UpperCardinalities.atMost(sumFiniteUpperBounds);
diff --git a/subprojects/store-query-interpreter/src/test/java/tools/refinery/store/query/interpreter/AggregatorBatchingTest.java b/subprojects/store-query-interpreter/src/test/java/tools/refinery/store/query/interpreter/AggregatorBatchingTest.java
index 209d7ac0..0bdd2148 100644
--- a/subprojects/store-query-interpreter/src/test/java/tools/refinery/store/query/interpreter/AggregatorBatchingTest.java
+++ b/subprojects/store-query-interpreter/src/test/java/tools/refinery/store/query/interpreter/AggregatorBatchingTest.java
@@ -5,6 +5,7 @@
  */
 package tools.refinery.store.query.interpreter;
 
+import org.jetbrains.annotations.NotNull;
 import org.junit.jupiter.api.Test;
 import tools.refinery.store.model.Model;
 import tools.refinery.store.model.ModelStore;
@@ -167,6 +168,7 @@ class AggregatorBatchingTest {
                         sum -= value;
                 }
 
+                @NotNull
                 @Override
                 public Integer getResult() {
                         extractCount++;