fix AggregatorFactory.finalizeComputation implementations to be ok with null inputs (#7731)

* AggregatorFactory finalizeComputation is nullable with nullable input, make implementations honor this

* fixes

extensions-contrib/distinctcount/src/main/java/org/apache/druid/query/aggregation/distinctcount/DistinctCountAggregatorFactory.java

@@ -35,6 +35,7 @@ import org.apache.druid.query.dimension.DefaultDimensionSpec;
 import org.apache.druid.segment.ColumnSelectorFactory;
 import org.apache.druid.segment.DimensionSelector;
 
+import javax.annotation.Nullable;
 import java.nio.ByteBuffer;
 import java.util.Collections;
 import java.util.Comparator;
@@ -147,8 +148,9 @@ public class DistinctCountAggregatorFactory extends AggregatorFactory
     return object;
   }
 
+  @Nullable
   @Override
-  public Object finalizeComputation(Object object)
+  public Object finalizeComputation(@Nullable Object object)
   {
     return object;
   }

extensions-contrib/momentsketch/src/main/java/org/apache/druid/query/aggregation/momentsketch/aggregator/MomentSketchAggregatorFactory.java

@@ -206,8 +206,9 @@ public class MomentSketchAggregatorFactory extends AggregatorFactory
     );
   }
 
+  @Nullable
   @Override
-  public Object finalizeComputation(Object object)
+  public Object finalizeComputation(@Nullable Object object)
   {
     return object;
   }

extensions-contrib/moving-average-query/src/main/java/org/apache/druid/query/movingaverage/AveragerFactoryWrapper.java

@@ -25,6 +25,7 @@ import org.apache.druid.query.aggregation.BufferAggregator;
 import org.apache.druid.query.movingaverage.averagers.AveragerFactory;
 import org.apache.druid.segment.ColumnSelectorFactory;
 
+import javax.annotation.Nullable;
 import java.util.Comparator;
 import java.util.List;
 
@@ -125,8 +126,9 @@ public class AveragerFactoryWrapper<T, R> extends AggregatorFactory
    * Not implemented. Throws UnsupportedOperationException.
    */
   @SuppressWarnings("unchecked")
+  @Nullable
   @Override
-  public Object finalizeComputation(Object object)
+  public Object finalizeComputation(@Nullable Object object)
   {
     return af.finalizeComputation((T) object);
   }

extensions-contrib/tdigestsketch/src/main/java/org/apache/druid/query/aggregation/tdigestsketch/TDigestBuildSketchAggregatorFactory.java

@@ -190,8 +190,9 @@ public class TDigestBuildSketchAggregatorFactory extends AggregatorFactory
     return TDigestSketchUtils.deserialize(serializedSketch);
   }
 
+  @Nullable
   @Override
-  public Object finalizeComputation(Object object)
+  public Object finalizeComputation(@Nullable Object object)
   {
     return object;
   }

extensions-contrib/time-min-max/src/main/java/org/apache/druid/query/aggregation/TimestampAggregatorFactory.java

@@ -27,6 +27,7 @@ import org.apache.druid.segment.ColumnSelectorFactory;
 import org.apache.druid.segment.ColumnValueSelector;
 import org.joda.time.DateTime;
 
+import javax.annotation.Nullable;
 import java.nio.ByteBuffer;
 import java.sql.Timestamp;
 import java.util.Collections;
@@ -157,10 +158,11 @@ public class TimestampAggregatorFactory extends AggregatorFactory
     return object;
   }
 
+  @Nullable
   @Override
-  public Object finalizeComputation(Object object)
+  public Object finalizeComputation(@Nullable Object object)
   {
-    return DateTimes.utc((long) object);
+    return object == null ? null : DateTimes.utc((long) object);
   }
 
   @Override

extensions-core/datasketches/src/main/java/org/apache/druid/query/aggregation/datasketches/hll/HllSketchAggregatorFactory.java

@@ -157,9 +157,13 @@ public abstract class HllSketchAggregatorFactory extends AggregatorFactory
     };
   }
 
+  @Nullable
   @Override
-  public Double finalizeComputation(final Object object)
+  public Double finalizeComputation(@Nullable final Object object)
   {
+    if (object == null) {
+      return null;
+    }
     final HllSketch sketch = (HllSketch) object;
     return sketch.getEstimate();
   }

extensions-core/datasketches/src/main/java/org/apache/druid/query/aggregation/datasketches/quantiles/DoublesSketchAggregatorFactory.java

@@ -240,10 +240,11 @@ public class DoublesSketchAggregatorFactory extends AggregatorFactory
     }
   }
 
+  @Nullable
   @Override
-  public Object finalizeComputation(final Object object)
+  public Object finalizeComputation(@Nullable final Object object)
   {
-    return ((DoublesSketch) object).getN();
+    return object == null ? null : ((DoublesSketch) object).getN();
   }
 
   @Override

extensions-core/datasketches/src/main/java/org/apache/druid/query/aggregation/datasketches/theta/SketchMergeAggregatorFactory.java

@@ -117,9 +117,14 @@ public class SketchMergeAggregatorFactory extends SketchAggregatorFactory
    *
    * @return sketch object
    */
+  @Nullable
   @Override
-  public Object finalizeComputation(Object object)
+  public Object finalizeComputation(@Nullable Object object)
   {
+    if (object == null) {
+      return null;
+    }
+
     if (shouldFinalize) {
       SketchHolder holder = (SketchHolder) object;
       if (errorBoundsStdDev != null) {

extensions-core/datasketches/src/main/java/org/apache/druid/query/aggregation/datasketches/tuple/ArrayOfDoublesSketchAggregatorFactory.java

@@ -285,10 +285,11 @@ public class ArrayOfDoublesSketchAggregatorFactory extends AggregatorFactory
     return new ArrayOfDoublesSketchAggregatorFactory(name, name, nominalEntries, null, numberOfValues);
   }
 
+  @Nullable
   @Override
-  public Object finalizeComputation(final Object object)
+  public Object finalizeComputation(@Nullable final Object object)
   {
-    return ((ArrayOfDoublesSketch) object).getEstimate();
+    return object == null ? null : ((ArrayOfDoublesSketch) object).getEstimate();
   }
 
   @Override

extensions-core/druid-bloom-filter/src/main/java/org/apache/druid/query/aggregation/bloom/BloomFilterAggregatorFactory.java

@@ -227,8 +227,9 @@ public class BloomFilterAggregatorFactory extends AggregatorFactory
     }
   }
 
+  @Nullable
   @Override
-  public Object finalizeComputation(Object object)
+  public Object finalizeComputation(@Nullable Object object)
   {
     return object;
   }

extensions-core/histogram/src/main/java/org/apache/druid/query/aggregation/histogram/ApproximateHistogramAggregatorFactory.java

@@ -214,10 +214,11 @@ public class ApproximateHistogramAggregatorFactory extends AggregatorFactory
     }
   }
 
+  @Nullable
   @Override
-  public Object finalizeComputation(Object object)
+  public Object finalizeComputation(@Nullable Object object)
   {
-    return ((ApproximateHistogram) object).toHistogram(numBuckets);
+    return object == null ? null : ((ApproximateHistogram) object).toHistogram(numBuckets);
   }
 
   @JsonProperty

extensions-core/stats/src/main/java/org/apache/druid/query/aggregation/variance/VarianceAggregatorFactory.java

@@ -39,6 +39,7 @@ import org.apache.druid.segment.ColumnSelectorFactory;
 import org.apache.druid.segment.ColumnValueSelector;
 import org.apache.druid.segment.NilColumnValueSelector;
 
+import javax.annotation.Nullable;
 import java.nio.ByteBuffer;
 import java.util.Collections;
 import java.util.Comparator;
@@ -202,10 +203,11 @@ public class VarianceAggregatorFactory extends AggregatorFactory
     return VarianceAggregatorCollector.COMPARATOR;
   }
 
+  @Nullable
   @Override
-  public Object finalizeComputation(Object object)
+  public Object finalizeComputation(@Nullable Object object)
   {
-    return ((VarianceAggregatorCollector) object).getVariance(isVariancePop);
+    return object == null ? null : ((VarianceAggregatorCollector) object).getVariance(isVariancePop);
   }
 
   @Override

processing/src/main/java/org/apache/druid/query/aggregation/CountAggregatorFactory.java

@@ -25,6 +25,7 @@ import com.google.common.base.Preconditions;
 import com.google.common.collect.ImmutableList;
 import org.apache.druid.segment.ColumnSelectorFactory;
 
+import javax.annotation.Nullable;
 import java.util.Collections;
 import java.util.Comparator;
 import java.util.List;
@@ -93,8 +94,9 @@ public class CountAggregatorFactory extends AggregatorFactory
     return object;
   }
 
+  @Nullable
   @Override
-  public Object finalizeComputation(Object object)
+  public Object finalizeComputation(@Nullable Object object)
   {
     return object;
   }

processing/src/main/java/org/apache/druid/query/aggregation/FilteredAggregatorFactory.java

@@ -32,6 +32,7 @@ import org.apache.druid.segment.column.ColumnHolder;
 import org.apache.druid.segment.filter.Filters;
 import org.joda.time.Interval;
 
+import javax.annotation.Nullable;
 import java.nio.ByteBuffer;
 import java.util.ArrayList;
 import java.util.Comparator;
@@ -118,8 +119,9 @@ public class FilteredAggregatorFactory extends AggregatorFactory
     return delegate.deserialize(object);
   }
 
+  @Nullable
   @Override
-  public Object finalizeComputation(Object object)
+  public Object finalizeComputation(@Nullable Object object)
   {
     return delegate.finalizeComputation(object);
   }

processing/src/main/java/org/apache/druid/query/aggregation/HistogramAggregatorFactory.java

@@ -154,10 +154,11 @@ public class HistogramAggregatorFactory extends AggregatorFactory
     return object;
   }
 
+  @Nullable
   @Override
-  public Object finalizeComputation(Object object)
+  public Object finalizeComputation(@Nullable Object object)
   {
-    return ((Histogram) object).asVisual();
+    return object == null ? null : ((Histogram) object).asVisual();
   }
 
   @Override

processing/src/main/java/org/apache/druid/query/aggregation/JavaScriptAggregatorFactory.java

@@ -35,6 +35,7 @@ import org.apache.druid.segment.ColumnSelectorFactory;
 import org.apache.druid.segment.ColumnValueSelector;
 import org.checkerframework.checker.nullness.qual.EnsuresNonNull;
 import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 import org.mozilla.javascript.Context;
 import org.mozilla.javascript.ContextAction;
 import org.mozilla.javascript.ContextFactory;
@@ -202,8 +203,9 @@ public class JavaScriptAggregatorFactory extends AggregatorFactory
     return object;
   }
 
+  @Nullable
   @Override
-  public Object finalizeComputation(Object object)
+  public Object finalizeComputation(@Nullable Object object)
   {
     return object;
   }

processing/src/main/java/org/apache/druid/query/aggregation/SuppressedAggregatorFactory.java

@@ -104,8 +104,9 @@ public class SuppressedAggregatorFactory extends AggregatorFactory
     return delegate.deserialize(object);
   }
 
+  @Nullable
   @Override
-  public Object finalizeComputation(Object object)
+  public Object finalizeComputation(@Nullable Object object)
   {
     return delegate.finalizeComputation(object);
   }

processing/src/main/java/org/apache/druid/query/aggregation/cardinality/CardinalityAggregatorFactory.java

@@ -44,6 +44,7 @@ import org.apache.druid.query.dimension.DimensionSpec;
 import org.apache.druid.segment.ColumnSelectorFactory;
 import org.apache.druid.segment.DimensionHandlerUtils;
 
+import javax.annotation.Nullable;
 import java.nio.ByteBuffer;
 import java.util.Collections;
 import java.util.Comparator;
@@ -234,9 +235,9 @@ public class CardinalityAggregatorFactory extends AggregatorFactory
     return HyperLogLogCollector.makeCollector(buffer);
   }
 
+  @Nullable
   @Override
-
+  public Object finalizeComputation(@Nullable Object object)
-  public Object finalizeComputation(Object object)
   {
     return HyperUniquesAggregatorFactory.estimateCardinality(object, round);
   }

processing/src/main/java/org/apache/druid/query/aggregation/first/StringFirstAggregatorFactory.java

@@ -36,6 +36,7 @@ import org.apache.druid.segment.BaseObjectColumnValueSelector;
 import org.apache.druid.segment.ColumnSelectorFactory;
 import org.apache.druid.segment.column.ColumnHolder;
 
+import javax.annotation.Nullable;
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.Comparator;
@@ -171,10 +172,11 @@ public class StringFirstAggregatorFactory extends NullableAggregatorFactory<Base
     return new SerializablePairLongString(((Number) map.get("lhs")).longValue(), ((String) map.get("rhs")));
   }
 
+  @Nullable
   @Override
-  public Object finalizeComputation(Object object)
+  public Object finalizeComputation(@Nullable Object object)
   {
-    return ((SerializablePairLongString) object).rhs;
+    return object == null ? null : ((SerializablePairLongString) object).rhs;
   }
 
   @Override

processing/src/main/java/org/apache/druid/query/aggregation/hyperloglog/HyperUniquesAggregatorFactory.java

@@ -39,6 +39,7 @@ import org.apache.druid.segment.BaseObjectColumnValueSelector;
 import org.apache.druid.segment.ColumnSelectorFactory;
 import org.apache.druid.segment.NilColumnValueSelector;
 
+import javax.annotation.Nullable;
 import java.nio.ByteBuffer;
 import java.util.Collections;
 import java.util.Comparator;
@@ -49,7 +50,7 @@ import java.util.Objects;
  */
 public class HyperUniquesAggregatorFactory extends AggregatorFactory
 {
-  public static Object estimateCardinality(Object object, boolean round)
+  public static Object estimateCardinality(@Nullable Object object, boolean round)
   {
     if (object == null) {
       return 0;
@@ -192,8 +193,9 @@ public class HyperUniquesAggregatorFactory extends AggregatorFactory
     return HyperLogLogCollector.makeCollector(buffer);
   }
 
+  @Nullable
   @Override
-  public Object finalizeComputation(Object object)
+  public Object finalizeComputation(@Nullable Object object)
   {
     return estimateCardinality(object, round);
   }

processing/src/main/java/org/apache/druid/query/aggregation/last/StringLastAggregatorFactory.java

@@ -36,6 +36,7 @@ import org.apache.druid.segment.BaseObjectColumnValueSelector;
 import org.apache.druid.segment.ColumnSelectorFactory;
 import org.apache.druid.segment.column.ColumnHolder;
 
+import javax.annotation.Nullable;
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.Comparator;
@@ -129,10 +130,11 @@ public class StringLastAggregatorFactory extends NullableAggregatorFactory<BaseO
     return new SerializablePairLongString(((Number) map.get("lhs")).longValue(), ((String) map.get("rhs")));
   }
 
+  @Nullable
   @Override
-  public Object finalizeComputation(Object object)
+  public Object finalizeComputation(@Nullable Object object)
   {
-    return ((SerializablePairLongString) object).rhs;
+    return object == null ? null : ((SerializablePairLongString) object).rhs;
   }
 
   @Override