Add missing override annotations.

src/main/java/io/github/vmzakharov/ecdataframe/dataframe/DfDateColumn.java

@@ -20,6 +20,7 @@ default String getValueAsString(int rowIndex)
         return value == null ? "" : this.FORMATTER.format(value);
     }
 
+    @Override
     default ValueType getType()
     {
         return ValueType.DATE;

src/main/java/io/github/vmzakharov/ecdataframe/dataframe/DfDateTimeColumn.java

@@ -20,6 +20,7 @@ default String getValueAsString(int rowIndex)
         return value == null ? "" : this.FORMATTER.format(value);
     }
 
+    @Override
     default ValueType getType()
     {
         return ValueType.DATE_TIME;

src/main/java/io/github/vmzakharov/ecdataframe/dataframe/DfDecimalColumn.java

@@ -17,6 +17,7 @@ default String getValueAsString(int rowIndex)
         return value == null ? "" : value.toString();
     }
 
+    @Override
     default ValueType getType()
     {
         return ValueType.DECIMAL;

src/main/java/io/github/vmzakharov/ecdataframe/dataframe/DfDoubleColumn.java

@@ -36,6 +36,7 @@ public ImmutableDoubleList toDoubleList()
             .toImmutable();
     }
 
+    @Override
     public ValueType getType()
     {
         return ValueType.DOUBLE;
@@ -65,6 +66,7 @@ public DfColumn mergeWithInto(DfColumn other, DataFrame target)
         return mergedCol;
     }
 
+    @Override
     public DfColumn copyTo(DataFrame target)
     {
         DfDoubleColumn targetCol = (DfDoubleColumn) this.copyColumnSchemaAndEnsureCapacity(target);

src/main/java/io/github/vmzakharov/ecdataframe/dataframe/DfDoubleColumnStored.java

@@ -83,6 +83,7 @@ public Object getObject(int rowIndex)
         return this.getDoubleWithoutNullCheck(rowIndex);
     }
 
+    @Override
     public double getDouble(int rowIndex)
     {
         if (this.isNull(rowIndex))
@@ -128,6 +129,7 @@ public void addEmptyValue()
         this.values.add(Double.NaN);
     }
 
+    @Override
     public void aggregateValueInto(int rowIndex, DfColumn sourceColumn, int sourceRowIndex, AggregateFunction aggregator)
     {
         aggregator.aggregateValueIntoDouble(this, rowIndex, sourceColumn, sourceRowIndex);

src/main/java/io/github/vmzakharov/ecdataframe/dataframe/DfFloatColumn.java

@@ -36,6 +36,7 @@ public ImmutableFloatList toFloatList()
                 .toImmutable();
     }
 
+    @Override
     public ValueType getType()
     {
         return ValueType.FLOAT;
@@ -65,6 +66,7 @@ public DfColumn mergeWithInto(DfColumn other, DataFrame target)
         return mergedCol;
     }
 
+    @Override
     public DfColumn copyTo(DataFrame target)
     {
         DfFloatColumn targetCol = (DfFloatColumn)  this.copyColumnSchemaAndEnsureCapacity(target);

src/main/java/io/github/vmzakharov/ecdataframe/dataframe/DfFloatColumnStored.java

@@ -82,6 +82,7 @@ public Object getObject(int rowIndex)
         return this.getFloatWithoutNullCheck(rowIndex);
     }
 
+    @Override
     public float getFloat(int rowIndex)
     {
         if (this.isNull(rowIndex))
@@ -127,6 +128,7 @@ public void addEmptyValue()
         this.values.add(Float.NaN);
     }
 
+    @Override
     public void aggregateValueInto(int rowIndex, DfColumn sourceColumn, int sourceRowIndex, AggregateFunction aggregator)
     {
         aggregator.aggregateValueIntoFloat(this, rowIndex, sourceColumn, sourceRowIndex);

src/main/java/io/github/vmzakharov/ecdataframe/dataframe/DfIntColumn.java

@@ -36,6 +36,7 @@ public ImmutableIntList toIntList()
                 .toImmutable();
     }
 
+    @Override
     public ValueType getType()
     {
         return ValueType.INT;
@@ -65,6 +66,7 @@ public DfColumn mergeWithInto(DfColumn other, DataFrame target)
         return mergedCol;
     }
 
+    @Override
     public DfColumn copyTo(DataFrame target)
     {
         DfIntColumn targetCol = (DfIntColumn)  this.copyColumnSchemaAndEnsureCapacity(target);

src/main/java/io/github/vmzakharov/ecdataframe/dataframe/DfIntColumnStored.java

@@ -58,6 +58,7 @@ public void addInt(int anInt, boolean isNullValue)
         this.nullMap.add(isNullValue);
     }
 
+    @Override
     public int getInt(int rowIndex)
     {
         if (this.isNull(rowIndex))
@@ -137,6 +138,7 @@ private void setNull(int rowIndex)
         this.nullMap.set(rowIndex, true);
     }
 
+    @Override
     public Object getObject(int rowIndex)
     {
         if (this.isNull(rowIndex))

src/main/java/io/github/vmzakharov/ecdataframe/dataframe/DfLongColumn.java

@@ -36,6 +36,7 @@ public ImmutableLongList toLongList()
                 .toImmutable();
     }
 
+    @Override
     public ValueType getType()
     {
         return ValueType.LONG;
@@ -65,6 +66,7 @@ public DfColumn mergeWithInto(DfColumn other, DataFrame target)
         return mergedCol;
     }
 
+    @Override
     public DfColumn copyTo(DataFrame target)
     {
         DfLongColumn targetCol = (DfLongColumn)  this.copyColumnSchemaAndEnsureCapacity(target);

src/main/java/io/github/vmzakharov/ecdataframe/dataframe/DfLongColumnStored.java

@@ -58,6 +58,7 @@ public void addLong(long aLong, boolean isNullValue)
         this.nullMap.add(isNullValue);
     }
 
+    @Override
     public long getLong(int rowIndex)
     {
         if (this.isNull(rowIndex))
@@ -137,6 +138,7 @@ private void setNull(int rowIndex)
         this.nullMap.set(rowIndex, true);
     }
 
+    @Override
     public Object getObject(int rowIndex)
     {
         if (this.isNull(rowIndex))

src/main/java/io/github/vmzakharov/ecdataframe/dataframe/DfObjectColumnAbstract.java

@@ -29,6 +29,7 @@ public DfColumn mergeWithInto(DfColumn other, DataFrame target)
         return mergedCol;
     }
 
+    @Override
     public DfColumn copyTo(DataFrame target)
     {
         DfObjectColumnAbstract<T> targetCol = (DfObjectColumnAbstract<T>) this.copyColumnSchemaAndEnsureCapacity(target);

src/main/java/io/github/vmzakharov/ecdataframe/dataframe/DfStringColumn.java

@@ -21,6 +21,7 @@ default String getValueAsStringLiteral(int rowIndex)
         return value == null ? "" : '"' + this.getValueAsString(rowIndex) + '"';
     }
 
+    @Override
     default ValueType getType()
     {
         return ValueType.STRING;

src/main/java/io/github/vmzakharov/ecdataframe/dsl/ArithmeticOp.java

@@ -132,6 +132,7 @@ public String asString()
         }
     };
 
+    @Override
     default Value apply(Value operand1, Value operand2)
     {
         if (operand1.isVoid() || operand2.isVoid())

src/main/java/io/github/vmzakharov/ecdataframe/dsl/ComparisonOp.java

@@ -59,6 +59,7 @@ public String asString()
 
     ComparisonOp NE = new ComparisonOp()
     {
+        @Override
         public BooleanValue apply(Value operand1, Value operand2)
         {
             if (operand1.isVoid())

src/main/java/io/github/vmzakharov/ecdataframe/dsl/FunctionScript.java

@@ -21,6 +21,7 @@ public FunctionScript(String newName, ListIterable<String> newParameterNames)
         this.parameterNames = newParameterNames;
     }
 
+    @Override
     public String getName()
     {
         return this.name;
@@ -43,6 +44,7 @@ public Value evaluate(ExpressionEvaluationVisitor evaluationVisitor)
         return evaluationVisitor.visitFunctionScriptExpr(this);
     }
 
+    @Override
     public ListIterable<String> getParameterNames()
     {
         return this.parameterNames;

src/main/java/io/github/vmzakharov/ecdataframe/dsl/PredicateOp.java

@@ -12,6 +12,7 @@
 public interface PredicateOp
 extends BinaryOp
 {
+    @Override
     default BooleanValue apply(Value operand1, Value operand2)
     {
         if (operand1.isVoid() || operand2.isVoid())

src/main/java/io/github/vmzakharov/ecdataframe/dsl/UnaryOp.java

@@ -57,6 +57,7 @@ public BooleanValue applyBoolean(boolean operand)
             return BooleanValue.valueOf(!operand);
         }
 
+        @Override
         public String asString()
         {
             return "!";

src/main/java/io/github/vmzakharov/ecdataframe/dsl/function/IntrinsicFunctionDescriptor.java

@@ -29,6 +29,7 @@ public IntrinsicFunctionDescriptor(String newName)
         this(newName, Lists.immutable.empty());
     }
 
+    @Override
     public String getName()
     {
         return this.name;
@@ -44,6 +45,7 @@ protected void setParameterNames(ListIterable<String> newParameterNames)
         this.parameterNames = newParameterNames;
     }
 
+    @Override
     public ListIterable<String> getParameterNames()
     {
         return this.parameterNames;

src/main/java/io/github/vmzakharov/ecdataframe/dsl/value/DecimalValue.java

@@ -51,6 +51,7 @@ public ValueType getType()
         return ValueType.DECIMAL;
     }
 
+    @Override
     public BigDecimal decimalValue()
     {
         return this.value;

src/main/java/io/github/vmzakharov/ecdataframe/dsl/value/DoubleValue.java

@@ -9,6 +9,7 @@
 public record DoubleValue(double value)
 implements RealNumberValue
 {
+    @Override
     public double doubleValue()
     {
         return this.value;

src/main/java/io/github/vmzakharov/ecdataframe/dsl/value/FloatValue.java

@@ -14,6 +14,7 @@ public float floatValue()
         return this.value;
     }
 
+    @Override
     public double doubleValue()
     {
         return this.value;

src/main/java/io/github/vmzakharov/ecdataframe/dsl/value/IntValue.java

@@ -32,6 +32,7 @@ public long longValue()
         return this.value;
     }
 
+    @Override
     public BigDecimal decimalValue()
     {
         return BigDecimal.valueOf(this.value);

src/main/java/io/github/vmzakharov/ecdataframe/dsl/value/LongValue.java

@@ -27,6 +27,7 @@ public double doubleValue()
         return this.value;
     }
 
+    @Override
     public BigDecimal decimalValue()
     {
         return BigDecimal.valueOf(this.value);

src/test/java/io/github/vmzakharov/ecdataframe/dataframe/DataFrameAggregationNullsAreOkayTest.java

@@ -150,6 +150,7 @@ public long longInitialValue()
             return 0;
         }
 
+        @Override
         public long getLongValue(DfColumn sourceColumn, int sourceRowIndex)
         {
             return sourceColumn.isNull(sourceRowIndex) ? 1 : 0;

src/test/java/io/github/vmzakharov/ecdataframe/dataframe/DataFrameAggregationWithCustomFunctionsTest.java

@@ -90,6 +90,7 @@ public SumStringLength(String newColumnName, String newTargetColumnName)
             super(newColumnName, newTargetColumnName);
         }
 
+        @Override
         public ListIterable<ValueType> supportedSourceTypes()
         {
             return Lists.immutable.of(STRING);
@@ -144,6 +145,7 @@ public Concat(String newColumnName, String newTargetColumnName)
             super(newColumnName, newTargetColumnName);
         }
 
+        @Override
         public ListIterable<ValueType> supportedSourceTypes()
         {
             return Lists.immutable.of(STRING);