Formatting, remove unnecessary constructors

h2/src/main/org/h2/expression/Aggregate.java

@@ -301,7 +301,7 @@ public class Aggregate extends Expression {
         }
         Value v = data.getValue(session.getDatabase(), dataType, distinct);
         if (type == GROUP_CONCAT) {
-            ArrayList<Value> list = ((AggregateDataGroupConcat)data).getList();
+            ArrayList<Value> list = ((AggregateDataGroupConcat) data).getList();
             if (list == null || list.size() == 0) {
                 return ValueNull.INSTANCE;
             }

h2/src/main/org/h2/expression/AggregateData.java

@@ -15,9 +15,10 @@ import org.h2.value.Value;
 abstract class AggregateData {
 
     /**
-     * Create an AggregateData object of the correct subtype.
+     * Create an AggregateData object of the correct sub-type.
      *
      * @param aggregateType the type of the aggregate operation
+     * @return the aggregate data object of the specified type
      */
     static AggregateData create(int aggregateType) {
         if (aggregateType == Aggregate.SELECTIVITY) {

h2/src/main/org/h2/expression/AggregateDataCount.java

@@ -18,8 +18,6 @@ class AggregateDataCount extends AggregateData {
     private long count;
     private ValueHashMap<AggregateDataCount> distinctValues;
 
-    AggregateDataCount() {}
-
     @Override
     void add(Database database, int dataType, boolean distinct, Value v) {
         if (v == ValueNull.INSTANCE) {

h2/src/main/org/h2/expression/AggregateDataCountAll.java

@@ -17,8 +17,6 @@ import org.h2.value.ValueNull;
 class AggregateDataCountAll extends AggregateData {
     private long count;
 
-    AggregateDataCountAll() {}
-
     @Override
     void add(Database database, int dataType, boolean distinct, Value v) {
         if (distinct) {

h2/src/main/org/h2/expression/AggregateDataGroupConcat.java

@@ -19,8 +19,6 @@ class AggregateDataGroupConcat extends AggregateData {
     private ArrayList<Value> list;
     private ValueHashMap<AggregateDataGroupConcat> distinctValues;
 
-    AggregateDataGroupConcat() {}
-
     @Override
     void add(Database database, int dataType, boolean distinct, Value v) {
         if (v == ValueNull.INSTANCE) {

h2/src/main/org/h2/expression/AggregateDataHistogram.java

@@ -22,8 +22,6 @@ class AggregateDataHistogram extends AggregateData {
     private long count;
     private ValueHashMap<AggregateDataHistogram> distinctValues;
 
-    AggregateDataHistogram() {}
-
     @Override
     void add(Database database, int dataType, boolean distinct, Value v) {
         if (distinctValues == null) {

h2/src/main/org/h2/expression/AggregateDataSelectivity.java

@@ -20,8 +20,6 @@ class AggregateDataSelectivity extends AggregateData {
     private IntIntHashMap distinctHashes;
     private double m2;
 
-    AggregateDataSelectivity() {}
-
     @Override
     void add(Database database, int dataType, boolean distinct, Value v) {
         count++;