Description
An expression that takes values from two or more fields and returns the the sum of all values
Example
<expression name="Sum\_Column_1_2_3" class="org.jfree.report.function.ColumnSumExpression">
<properties>
<property name="field\[0\]">Column_1</property>
<property name="field\[1\]">Column_2</property>
<property name="field\[2\]">Column_3</property>
</properties>
</expression>