Fixed: Code refactoring to support groovy syntax

(OFBIZ-10231)

No functional change

This commit contains multiple refactoring to decrease code quantity :
 * use groovy syntax for empty/not empty value
 * use kelvin syntax
 * exploit DSL syntax and EntityQuery as possible
 * refactoring redundant "if block"
 * remove unnecessary transfer variable

Thanks to Gil Portenseigne for help my as his second eye