Migration to Isabelle 2020.

.ci/Jenkinsfile

@@ -3,7 +3,7 @@ pipeline {
     stages {
         stage('Build') {
             steps {
-                sh 'docker run -v $PWD/Featherweight_OCL:/Featherweight_OCL logicalhacking:isabelle2019 isabelle build -D /Featherweight_OCL'
+                sh 'docker run -v $PWD/Featherweight_OCL:/Featherweight_OCL logicalhacking:isabelle2020 isabelle build -D /Featherweight_OCL'
             }
         }
     }

Featherweight_OCL/ROOT

@@ -1,9 +1,14 @@
 chapter AFP
 
-session "Featherweight_OCL-devel" (AFP) = HOL +
+session Featherweight_OCL-devel (AFP) = HOL +
   description "Featherweight-OCL"
   options [document_variants = "annex-a=annexa,-theory,-afp,-proof,-ML:document=afp,-annexa:outline=-annexa,afp,/proof,/ML",
            show_question_marks = false, timeout = 600]
+  directories
+    "basic_types"
+    "collection_types"
+    "examples/Employee_Model/Analysis"
+    "examples/Employee_Model/Design"
   theories
     UML_Main
     "examples/Employee_Model/Analysis/Analysis_OCL"