You are using the JExcelApiExporter. It is using the JExcelApi library.
You can check the dependency in the JasperReports's pom.xml file. The JasperReports 5.2 is using this artifact:
<dependency>
<groupId>net.sourceforge.jexcelapi</groupId>
<artifactId>jxl</artifactId>
<version>2.6.10</version>
</dependency>
It means that you should add jxl-2.6.10.jar to your application classpath (in case using JasperReports 5.2).