<<if [CustomerDetails != null && !CustomerDetails.isEmpty()]>><<foreach [customer in CustomerDetails]>> First Name: <<[customer.firstName]>>
Last Name: <<[customer.lastName]>>
Email Address: <<[customer.emailAddress]>>
<</foreach>> 
<</if>>

..i use this syntax its working and in java

ReportingEngine engine = new ReportingEngine();
      
        engine.buildReport(doc, customerData);