This was posted on StackOverflow with no working answer so I thought I'd try here:
Create a new project: Hello World (Bare Bones)
add new: Gui Builder, form, hit finish
error: Unresolved compilation problem: '<>' operator is not allowed for source level below 1.7
java version is oracle's 1.8.0_91
eclipse.ini includes: -Dosgi.requiredJavaVersion=1.8
build.xml has all source and target lines set to 1.8 (they were that way already)
CodenameOne build hints java.version is set to 8 (it was that way already)
CodenameOne 3.4
IDE: Eclipse Mars
Desktop OS: Ubunut 16.04
Simulator : none yet
Device: none yet