diff --git a/bin/ci/python-experimental.json b/bin/ci/python-experimental.json
new file mode 100644
index 00000000000..d9f6d70db22
--- /dev/null
+++ b/bin/ci/python-experimental.json
@@ -0,0 +1,9 @@
+{
+  "generatorName": "python-experimental",
+  "inputSpec": "modules/openapi-generator/src/test/resources/2_0/python-client-experimental/petstore-with-fake-endpoints-models-for-testing.yaml",
+  "outputDir": "samples/client/petstore/python-experimental",
+  "templateDir": "modules/openapi-generator/src/main/resources/python",
+  "additionalProperties": {
+    "packageName": "petstore_api"
+  }
+}
\ No newline at end of file
diff --git a/bin/ci/spring-petstore-8.json b/bin/ci/spring-petstore-8.json
index d275fbabac9..840e4fa8c4a 100644
--- a/bin/ci/spring-petstore-8.json
+++ b/bin/ci/spring-petstore-8.json
@@ -5,6 +5,7 @@
   "outputDir": "samples/server/petstore/springboot",
   "templateDir": "modules/openapi-generator/src/main/resources/JavaSpring",
   "additionalProperties": {
-    "hideGenerationTimestamp": true
+    "hideGenerationTimestamp": true,
+    "snapshotVersion": true
   }
 }
\ No newline at end of file
diff --git a/bin/meta-codegen-kotlin.sh b/bin/meta-codegen-kotlin.sh
index 5df67a9dab5..347d8f76144 100755
--- a/bin/meta-codegen-kotlin.sh
+++ b/bin/meta-codegen-kotlin.sh
@@ -1,52 +1,40 @@
-#!/bin/sh
+#!/usr/bin/env bash
 
 SCRIPT="$0"
 echo "# START SCRIPT: $SCRIPT"
 
+declare cwd="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+declare root="$(cd "$cwd" && cd ../ && pwd)"
+
 if ! command -v gradle > /dev/null; then
 		echo "[WARN] This script requires a system gradle to be installed. Not treating this as an error."
 		exit 0
 fi
 
-while [ -h "$SCRIPT" ] ; do
-  ls=`ls -ld "$SCRIPT"`
-  link=`expr "$ls" : '.*-> \(.*\)$'`
-  if expr "$link" : '/.*' > /dev/null; then
-    SCRIPT="$link"
-  else
-    SCRIPT=`dirname "$SCRIPT"`/"$link"
-  fi
-done
-
-if [ ! -d "${APP_DIR}" ]; then
-  APP_DIR=`dirname "$SCRIPT"`/..
-  APP_DIR=`cd "${APP_DIR}"; pwd`
-fi
-
-executable="./modules/openapi-generator-cli/target/openapi-generator-cli.jar"
+executable="${root}/modules/openapi-generator-cli/target/openapi-generator-cli.jar"
 
 if [ ! -f "$executable" ]
 then
-  ./mvnw -B clean package
+  (cd "$root" && ./mvnw -B clean package)
 fi
 
-\rm -rf "samples/meta-codegen-kotlin/lib"
+\rm -rf "${root}/samples/meta-codegen-kotlin/lib"
 
 export JAVA_OPTS="${JAVA_OPTS} -Xmx1024M -DloggerPath=conf/log4j.properties"
 ags="meta -n myClientCodegen -t DOCUMENTATION -p com.my.company.codegen -o samples/meta-codegen-kotlin/lib -l kotlin $@"
 
 java $JAVA_OPTS -jar $executable $ags
 
-if [ ! -f samples/meta-codegen-kotlin/gradle/wrapper/gradle-wrapper.jar ]; then
-  (cd samples/meta-codegen-kotlin/ && gradle wrapper --gradle-version 5.6.2 --distribution-type bin)
+if [ ! -f "${root}"samples/meta-codegen-kotlin/gradle/wrapper/gradle-wrapper.jar ]; then
+  (cd "${root}"/samples/meta-codegen-kotlin/ && gradle wrapper --gradle-version 5.6.2 --distribution-type bin)
 fi
 
 
-(cp samples/meta-codegen-kotlin/gradlew samples/meta-codegen-kotlin/lib/ && \
- cp -R samples/meta-codegen-kotlin/gradle samples/meta-codegen-kotlin/lib/ && \
-  cd samples/meta-codegen-kotlin/lib && \
+(cp "${root}"/samples/meta-codegen-kotlin/gradlew "${root}"/samples/meta-codegen-kotlin/lib/ && \
+ cp -R "${root}"/samples/meta-codegen-kotlin/gradle "${root}"/samples/meta-codegen-kotlin/lib/ && \
+  cd "${root}"/samples/meta-codegen-kotlin/lib && \
   ./gradlew shadowJar)
 
 ags2="generate -g myClientCodegen -i modules/openapi-generator/src/test/resources/2_0/petstore.json -o samples/meta-codegen-kotlin/usage $@"
 
-java $JAVA_OPTS -cp samples/meta-codegen-kotlin/lib/build/libs/my-client-codegen-openapi-generator-1.0-SNAPSHOT-all.jar:$executable org.openapitools.codegen.OpenAPIGenerator $ags2
+java $JAVA_OPTS -cp ${root}/samples/meta-codegen-kotlin/lib/build/libs/my-client-codegen-openapi-generator-1.0-SNAPSHOT-all.jar:$executable org.openapitools.codegen.OpenAPIGenerator $ags2
diff --git a/bin/meta-codegen.sh b/bin/meta-codegen.sh
index 2c36acc1400..f45875ea3ae 100755
--- a/bin/meta-codegen.sh
+++ b/bin/meta-codegen.sh
@@ -1,28 +1,15 @@
-#!/bin/sh
+#!/usr/bin/env bash
 
 SCRIPT="$0"
 echo "# START SCRIPT: $SCRIPT"
 
-while [ -h "$SCRIPT" ] ; do
-  ls=`ls -ld "$SCRIPT"`
-  link=`expr "$ls" : '.*-> \(.*\)$'`
-  if expr "$link" : '/.*' > /dev/null; then
-    SCRIPT="$link"
-  else
-    SCRIPT=`dirname "$SCRIPT"`/"$link"
-  fi
-done
+declare cwd="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+declare root="$(cd "$cwd" && cd ../ && pwd)"
 
-if [ ! -d "${APP_DIR}" ]; then
-  APP_DIR=`dirname "$SCRIPT"`/..
-  APP_DIR=`cd "${APP_DIR}"; pwd`
-fi
+executable="${root}/modules/openapi-generator-cli/target/openapi-generator-cli.jar"
 
-executable="./modules/openapi-generator-cli/target/openapi-generator-cli.jar"
-
-if [ ! -f "$executable" ]
-then
-  ./mvnw -B clean package
+if [ ! -f "$executable" ]; then
+  (cd "$root" && ./mvnw -B clean package)
 fi
 
 export JAVA_OPTS="${JAVA_OPTS} -Xmx1024M -DloggerPath=conf/log4j.properties"
@@ -30,8 +17,8 @@ ags="meta -n myClientCodegen -t DOCUMENTATION -p com.my.company.codegen -o sampl
 
 java $JAVA_OPTS -jar $executable $ags
 
-./mvnw clean package -f samples/meta-codegen/pom.xml
+(cd "$root" && ./mvnw clean package -f samples/meta-codegen/pom.xml)
 
 ags2="generate -g myClientCodegen -i modules/openapi-generator/src/test/resources/2_0/petstore.json -o samples/meta-codegen/usage $@"
 
-java $JAVA_OPTS -cp samples/meta-codegen/lib/target/myClientCodegen-openapi-generator-1.0.0.jar:$executable org.openapitools.codegen.OpenAPIGenerator $ags2
+java $JAVA_OPTS -cp ${root}/samples/meta-codegen/lib/target/myClientCodegen-openapi-generator-1.0.0.jar:$executable org.openapitools.codegen.OpenAPIGenerator $ags2
diff --git a/bin/utils/ensure-up-to-date b/bin/utils/ensure-up-to-date
index 425fe57485d..f1ee2f60718 100755
--- a/bin/utils/ensure-up-to-date
+++ b/bin/utils/ensure-up-to-date
@@ -21,9 +21,7 @@ echo "Please press CTRL+C to stop or the script will continue in 5 seconds."
 
 sleep 5
 
-# LIST OF SCRIPTS:
-declare -a scripts=(
-# SAMPLES
+declare -a samples=(
 "${root}/bin/ruby-client-petstore.sh"
 "${root}/bin/ruby-client-petstore-faraday.sh"
 "${root}/bin/openapi3/ruby-client-petstore.sh"
@@ -80,11 +78,16 @@ declare -a scripts=(
 "${root}/bin/dart2-petstore.sh"
 "${root}/bin/java-play-framework-petstore-server-all.sh"
 #"${root}/bin/elm-petstore-all.sh"
+)
+
+# Some special case generators may expect to be run as a stanalone process (e.g. modifying classpath)
+# Docs should always be run, regardless of batch or operation.
+declare -a always_iterate=(
 "${root}/bin/meta-codegen.sh"
-# OTHERS
 "${root}/bin/utils/export_docs_generators.sh"
 "${root}/bin/utils/copy-to-website.sh"
-"${root}/bin/utils/export_generators_readme.sh")
+"${root}/bin/utils/export_generators_readme.sh"
+)
 
 export JAVA_OPTS="${JAVA_OPTS} -Djava.awt.headless=true"
 
@@ -96,7 +99,7 @@ if [ "true" = "$batch_mode" ]; then
   # shellcheck disable=SC2086
   java $JAVA_OPTS -jar "$executable" batch --includes-base-dir "${root}" --fail-fast  -- "${root}"/bin/ci/*
 else
-  for script in "${scripts[@]}"; do
+  for script in "${samples[@]}"; do
     if eval "$script" > /dev/null 2>&1; then
       echo "Executed $script successfully!"
     else
@@ -106,6 +109,15 @@ else
   done
 fi
 
+for i in "${always_iterate[@]}"; do
+    if eval "$i" > /dev/null 2>&1; then
+      echo "Executed $i successfully!"
+    else
+      echo "ERROR: Failed to run $i"
+      exit 1
+    fi
+done
+
 # Check:
 if [ -n "$(git status --porcelain)" ]; then
     echo "UNCOMMITTED CHANGES ERROR"
@@ -119,3 +131,4 @@ if [ -n "$(git status --porcelain)" ]; then
 else
     echo "Git working tree is clean"
 fi
+
diff --git a/samples/client/petstore/python-experimental/.openapi-generator/VERSION b/samples/client/petstore/python-experimental/.openapi-generator/VERSION
index d168f1d8bda..e4955748d3e 100644
--- a/samples/client/petstore/python-experimental/.openapi-generator/VERSION
+++ b/samples/client/petstore/python-experimental/.openapi-generator/VERSION
@@ -1 +1 @@
-4.2.1-SNAPSHOT
\ No newline at end of file
+4.2.2-SNAPSHOT
\ No newline at end of file
diff --git a/samples/meta-codegen-kotlin/gradlew b/samples/meta-codegen-kotlin/gradlew
index cccdd3d517f..2fe81a7d95e 100755
--- a/samples/meta-codegen-kotlin/gradlew
+++ b/samples/meta-codegen-kotlin/gradlew
@@ -1,5 +1,21 @@
 #!/usr/bin/env sh
 
+#
+# Copyright 2015 the original author or authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
 ##############################################################################
 ##
 ##  Gradle start up script for UN*X
@@ -28,7 +44,7 @@ APP_NAME="Gradle"
 APP_BASE_NAME=`basename "$0"`
 
 # Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
-DEFAULT_JVM_OPTS=""
+DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
 
 # Use the maximum available, or set MAX_FD != -1 to use that value.
 MAX_FD="maximum"
@@ -109,8 +125,8 @@ if $darwin; then
     GRADLE_OPTS="$GRADLE_OPTS \"-Xdock:name=$APP_NAME\" \"-Xdock:icon=$APP_HOME/media/gradle.icns\""
 fi
 
-# For Cygwin, switch paths to Windows format before running java
-if $cygwin ; then
+# For Cygwin or MSYS, switch paths to Windows format before running java
+if [ "$cygwin" = "true" -o "$msys" = "true" ] ; then
     APP_HOME=`cygpath --path --mixed "$APP_HOME"`
     CLASSPATH=`cygpath --path --mixed "$CLASSPATH"`
     JAVACMD=`cygpath --unix "$JAVACMD"`
@@ -138,19 +154,19 @@ if $cygwin ; then
         else
             eval `echo args$i`="\"$arg\""
         fi
-        i=$((i+1))
+        i=`expr $i + 1`
     done
     case $i in
-        (0) set -- ;;
-        (1) set -- "$args0" ;;
-        (2) set -- "$args0" "$args1" ;;
-        (3) set -- "$args0" "$args1" "$args2" ;;
-        (4) set -- "$args0" "$args1" "$args2" "$args3" ;;
-        (5) set -- "$args0" "$args1" "$args2" "$args3" "$args4" ;;
-        (6) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" ;;
-        (7) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" ;;
-        (8) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" ;;
-        (9) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" "$args8" ;;
+        0) set -- ;;
+        1) set -- "$args0" ;;
+        2) set -- "$args0" "$args1" ;;
+        3) set -- "$args0" "$args1" "$args2" ;;
+        4) set -- "$args0" "$args1" "$args2" "$args3" ;;
+        5) set -- "$args0" "$args1" "$args2" "$args3" "$args4" ;;
+        6) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" ;;
+        7) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" ;;
+        8) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" ;;
+        9) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" "$args8" ;;
     esac
 fi
 
@@ -159,14 +175,9 @@ save () {
     for i do printf %s\\n "$i" | sed "s/'/'\\\\''/g;1s/^/'/;\$s/\$/' \\\\/" ; done
     echo " "
 }
-APP_ARGS=$(save "$@")
+APP_ARGS=`save "$@"`
 
 # Collect all arguments for the java command, following the shell quoting and substitution rules
 eval set -- $DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS "\"-Dorg.gradle.appname=$APP_BASE_NAME\"" -classpath "\"$CLASSPATH\"" org.gradle.wrapper.GradleWrapperMain "$APP_ARGS"
 
-# by default we should be in the correct project dir, but when run from Finder on Mac, the cwd is wrong
-if [ "$(uname)" = "Darwin" ] && [ "$HOME" = "$PWD" ]; then
-  cd "$(dirname "$0")"
-fi
-
 exec "$JAVACMD" "$@"
diff --git a/samples/meta-codegen-kotlin/gradlew.bat b/samples/meta-codegen-kotlin/gradlew.bat
index e95643d6a2c..24467a141f7 100644
--- a/samples/meta-codegen-kotlin/gradlew.bat
+++ b/samples/meta-codegen-kotlin/gradlew.bat
@@ -1,3 +1,19 @@
+@rem
+@rem Copyright 2015 the original author or authors.
+@rem
+@rem Licensed under the Apache License, Version 2.0 (the "License");
+@rem you may not use this file except in compliance with the License.
+@rem You may obtain a copy of the License at
+@rem
+@rem      https://www.apache.org/licenses/LICENSE-2.0
+@rem
+@rem Unless required by applicable law or agreed to in writing, software
+@rem distributed under the License is distributed on an "AS IS" BASIS,
+@rem WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+@rem See the License for the specific language governing permissions and
+@rem limitations under the License.
+@rem
+
 @if "%DEBUG%" == "" @echo off
 @rem ##########################################################################
 @rem
@@ -14,7 +30,7 @@ set APP_BASE_NAME=%~n0
 set APP_HOME=%DIRNAME%
 
 @rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
-set DEFAULT_JVM_OPTS=
+set DEFAULT_JVM_OPTS="-Xmx64m" "-Xms64m"
 
 @rem Find java.exe
 if defined JAVA_HOME goto findJavaFromJavaHome
diff --git a/samples/meta-codegen-kotlin/lib/gradlew b/samples/meta-codegen-kotlin/lib/gradlew
index cccdd3d517f..2fe81a7d95e 100755
--- a/samples/meta-codegen-kotlin/lib/gradlew
+++ b/samples/meta-codegen-kotlin/lib/gradlew
@@ -1,5 +1,21 @@
 #!/usr/bin/env sh
 
+#
+# Copyright 2015 the original author or authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
 ##############################################################################
 ##
 ##  Gradle start up script for UN*X
@@ -28,7 +44,7 @@ APP_NAME="Gradle"
 APP_BASE_NAME=`basename "$0"`
 
 # Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
-DEFAULT_JVM_OPTS=""
+DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
 
 # Use the maximum available, or set MAX_FD != -1 to use that value.
 MAX_FD="maximum"
@@ -109,8 +125,8 @@ if $darwin; then
     GRADLE_OPTS="$GRADLE_OPTS \"-Xdock:name=$APP_NAME\" \"-Xdock:icon=$APP_HOME/media/gradle.icns\""
 fi
 
-# For Cygwin, switch paths to Windows format before running java
-if $cygwin ; then
+# For Cygwin or MSYS, switch paths to Windows format before running java
+if [ "$cygwin" = "true" -o "$msys" = "true" ] ; then
     APP_HOME=`cygpath --path --mixed "$APP_HOME"`
     CLASSPATH=`cygpath --path --mixed "$CLASSPATH"`
     JAVACMD=`cygpath --unix "$JAVACMD"`
@@ -138,19 +154,19 @@ if $cygwin ; then
         else
             eval `echo args$i`="\"$arg\""
         fi
-        i=$((i+1))
+        i=`expr $i + 1`
     done
     case $i in
-        (0) set -- ;;
-        (1) set -- "$args0" ;;
-        (2) set -- "$args0" "$args1" ;;
-        (3) set -- "$args0" "$args1" "$args2" ;;
-        (4) set -- "$args0" "$args1" "$args2" "$args3" ;;
-        (5) set -- "$args0" "$args1" "$args2" "$args3" "$args4" ;;
-        (6) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" ;;
-        (7) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" ;;
-        (8) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" ;;
-        (9) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" "$args8" ;;
+        0) set -- ;;
+        1) set -- "$args0" ;;
+        2) set -- "$args0" "$args1" ;;
+        3) set -- "$args0" "$args1" "$args2" ;;
+        4) set -- "$args0" "$args1" "$args2" "$args3" ;;
+        5) set -- "$args0" "$args1" "$args2" "$args3" "$args4" ;;
+        6) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" ;;
+        7) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" ;;
+        8) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" ;;
+        9) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" "$args8" ;;
     esac
 fi
 
@@ -159,14 +175,9 @@ save () {
     for i do printf %s\\n "$i" | sed "s/'/'\\\\''/g;1s/^/'/;\$s/\$/' \\\\/" ; done
     echo " "
 }
-APP_ARGS=$(save "$@")
+APP_ARGS=`save "$@"`
 
 # Collect all arguments for the java command, following the shell quoting and substitution rules
 eval set -- $DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS "\"-Dorg.gradle.appname=$APP_BASE_NAME\"" -classpath "\"$CLASSPATH\"" org.gradle.wrapper.GradleWrapperMain "$APP_ARGS"
 
-# by default we should be in the correct project dir, but when run from Finder on Mac, the cwd is wrong
-if [ "$(uname)" = "Darwin" ] && [ "$HOME" = "$PWD" ]; then
-  cd "$(dirname "$0")"
-fi
-
 exec "$JAVACMD" "$@"