AgentSet cannot be resolved to type in Repast Simphony model

Question

I've installed Repast Simphony on Eclispe (centos 7.7) and I'm trying to run the Zombies demo but seeing errors like the following:

AbstractGridFunction cannot be resolved to a type   Heatbug.java    /Heatbugs/src/repast/model/heatbugs line 58 Java Problem
AbstractPointTranslator cannot be resolved to a type    SwarmBuilder.java   /Flock/src/flock/agents line 41 Java Problem
AbstractReLogoPanelCreator cannot be resolved to a type ReLogoPanelCreator.java /Zombies_Demo/src/zombies/factories line 7  Java Problem
AbstractStyleVisitor cannot be resolved to a type   BlueCoverageStyle.java  /Geography/src/geography/styles line 25 Java Problem
AgentAnnot cannot be resolved to a type SimpleAgent.java    /PredatorPrey/src/PredatorPrey/agents   line 19 Java Problem
AgentSet cannot be resolved to a type   ReLogoLink.java /Zombies_Demo/src-gen/zombies   line 25 Java Problem
AgentSet cannot be resolved to a type   ReLogoLink.java /Zombies_Demo/src-gen/zombies   line 26 Java Problem
AgentSet cannot be resolved to a type   ReLogoLink.java /Zombies_Demo/src-gen/zombies   line 26 Java Problem ```
 

Any suggestions on how to resolve this are appreciated.
Ed Hall