diff --git a/bin/utils/test-fake-petstore-for-all.sh b/bin/utils/test-fake-petstore-for-all.sh
new file mode 100755
index 00000000000..b9e1cc47f1e
--- /dev/null
+++ b/bin/utils/test-fake-petstore-for-all.sh
@@ -0,0 +1,28 @@
+#!/bin/bash
+#
+# A script to test all generators to ensure there's no Java exception when running it with OAS 2.0, 3.0 fake petstore spec
+#
+
+SCRIPT="$0"
+echo "# START SCRIPT: ${SCRIPT}"
+
+executable="./modules/openapi-generator-cli/target/openapi-generator-cli.jar"
+
+for GENERATOR in $(java -jar ${executable} list --short | sed -e 's/,/\'$'\n''/g')
+do
+    if eval java -jar ${executable} generate -i modules/openapi-generator/src/test/resources/2_0/petstore-with-fake-endpoints-models-for-testing.yaml -g ${GENERATOR} -o /tmp/openapi-generator-test-fake-petstore/2.0/${GENERATOR} > /dev/null 2>&1; then
+      echo "[OAS 2.0] Executed ${GENERATOR} successfully!"
+    else
+      echo "ERROR: Failed to run ${GENERATOR}"
+      echo "java -jar ${executable} generate -i modules/openapi-generator/src/test/resources/2_0/petstore-with-fake-endpoints-models-for-testing.yaml -g ${GENERATOR} -o /tmp/openapi-generator-test-fake-petstore/2.0/${GENERATOR}"
+      exit 1
+    fi
+
+    if eval java -jar ${executable} generate -i modules/openapi-generator/src/test/resources/2_0/petstore-with-fake-endpoints-models-for-testing.yaml -g ${GENERATOR} -o /tmp/openapi-generator-test-fake-petstore/3.0/${GENERATOR} > /dev/null 2>&1; then
+      echo "[OAS 3.0] Executed ${GENERATOR} successfully!"
+    else
+      echo "ERROR: Failed to run ${GENERATOR}"
+      echo "java -jar ${executable} generate -i modules/openapi-generator/src/test/resources/2_0/petstore-with-fake-endpoints-models-for-testing.yaml -g ${GENERATOR} -o /tmp/openapi-generator-test-fake-petstore/3.0/${GENERATOR}"
+      exit 1
+    fi
+done
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/ElmClientCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/ElmClientCodegen.java
index 07d06a03b04..1fcc2c77edb 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/ElmClientCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/ElmClientCodegen.java
@@ -261,7 +261,13 @@ public class ElmClientCodegen extends DefaultCodegen implements CodegenConfig {
 
     @Override
     public String toEnumVarName(String value, String datatype) {
-        final String camelized = org.openapitools.codegen.utils.StringUtils.camelize(value.replace(" ", "_").replace("(", "_").replace(")", "")); // TODO FIXME escape properly
+        String camelized = org.openapitools.codegen.utils.StringUtils.camelize(value.replace(" ", "_").replace("(", "_").replace(")", "")); // TODO FIXME escape properly
+
+        if (camelized.length() == 0) {
+            LOGGER.error("Unable to determine enum variable name (name: {}, datatype: {}) from empty string. Default to UnknownEnumVariableName", value, datatype);
+            camelized = "UnknownEnumVariableName";
+        }
+
         if (!Character.isUpperCase(camelized.charAt(0))) {
             return "N" + camelized;
         }
@@ -495,9 +501,8 @@ public class ElmClientCodegen extends DefaultCodegen implements CodegenConfig {
         } else if (ModelUtils.isDateTimeSchema(p)) {
             return toOptionalValue(null);
         } else if (ModelUtils.isNumberSchema(p)) {
-            NumberSchema dp = (NumberSchema) p;
-            if (dp.getDefault() != null) {
-                return toOptionalValue(dp.getDefault().toString());
+            if (p.getDefault() != null) {
+                return toOptionalValue(p.getDefault().toString());
             }
             return toOptionalValue(null);
         } else if (ModelUtils.isIntegerSchema(p)) {
diff --git a/modules/openapi-generator/src/main/resources/JavaJaxRS/resteasy/eap/allowableValues.mustache b/modules/openapi-generator/src/main/resources/JavaJaxRS/resteasy/eap/allowableValues.mustache
new file mode 100644
index 00000000000..a48256d027a
--- /dev/null
+++ b/modules/openapi-generator/src/main/resources/JavaJaxRS/resteasy/eap/allowableValues.mustache
@@ -0,0 +1 @@
+{{#allowableValues}}allowableValues="{{#values}}{{{.}}}{{^-last}}, {{/-last}}{{/values}}{{^values}}range=[{{#min}}{{.}}{{/min}}{{^min}}-infinity{{/min}}, {{#max}}{{.}}{{/max}}{{^max}}infinity{{/max}}]{{/values}}"{{/allowableValues}}
\ No newline at end of file
diff --git a/shippable.yml b/shippable.yml
index 85621905a47..0e463b9827e 100644
--- a/shippable.yml
+++ b/shippable.yml
@@ -44,3 +44,5 @@ build:
     - ./bin/openapi3/run-all-petstore
     # generate test scripts
     - ./bin/tests/run-all-test
+    # test all generators with fake petstore spec (2.0, 3.0)
+    - ./bin/utils/test-fake-petstore-for-all.sh