diff --git a/modules/openapi-generator/src/main/resources/android/build.mustache b/modules/openapi-generator/src/main/resources/android/build.mustache
index 1a5ba2185eaf..52f3c8861124 100644
--- a/modules/openapi-generator/src/main/resources/android/build.mustache
+++ b/modules/openapi-generator/src/main/resources/android/build.mustache
@@ -57,20 +57,8 @@ android {
         {{/androidSdkVersion}}
     }
     compileOptions {
-        {{#supportJava6}}
-        sourceCompatibility JavaVersion.VERSION_1_6
-        targetCompatibility JavaVersion.VERSION_1_6
-        {{/supportJava6}}
-        {{^supportJava6}}
-        {{#java8}}
         sourceCompatibility JavaVersion.VERSION_1_8
         targetCompatibility JavaVersion.VERSION_1_8
-        {{/java8}}
-        {{^java8}}
-        sourceCompatibility JavaVersion.VERSION_1_7
-        targetCompatibility JavaVersion.VERSION_1_7
-        {{/java8}}
-        {{/supportJava6}}
     }
 
     // Rename the aar correctly
diff --git a/modules/openapi-generator/src/main/resources/android/libraries/volley/build.mustache b/modules/openapi-generator/src/main/resources/android/libraries/volley/build.mustache
index 86933d07155b..30ceb9619f7c 100644
--- a/modules/openapi-generator/src/main/resources/android/libraries/volley/build.mustache
+++ b/modules/openapi-generator/src/main/resources/android/libraries/volley/build.mustache
@@ -41,20 +41,8 @@ android {
         targetSdkVersion 25
     }
     compileOptions {
-        {{#supportJava6}}
-        sourceCompatibility JavaVersion.VERSION_1_6
-        targetCompatibility JavaVersion.VERSION_1_6
-        {{/supportJava6}}
-        {{^supportJava6}}
-        {{#java8}}
         sourceCompatibility JavaVersion.VERSION_1_8
         targetCompatibility JavaVersion.VERSION_1_8
-        {{/java8}}
-        {{^java8}}
-        sourceCompatibility JavaVersion.VERSION_1_7
-        targetCompatibility JavaVersion.VERSION_1_7
-        {{/java8}}
-        {{/supportJava6}}
     }
     lintOptions {
         abortOnError false
diff --git a/modules/openapi-generator/src/main/resources/android/libraries/volley/pom.mustache b/modules/openapi-generator/src/main/resources/android/libraries/volley/pom.mustache
index d0cf3b56e965..bcf9d760766f 100644
--- a/modules/openapi-generator/src/main/resources/android/libraries/volley/pom.mustache
+++ b/modules/openapi-generator/src/main/resources/android/libraries/volley/pom.mustache
@@ -45,8 +45,8 @@
         <artifactId>maven-compiler-plugin</artifactId>
         <version>3.8.1</version>
         <configuration>
-          <source>{{#java8}}1.8{{/java8}}{{^java8}}1.7{{/java8}}</source>
-          <target>{{#java8}}1.8{{/java8}}{{^java8}}1.7{{/java8}}</target>
+          <source>1.8</source>
+          <target>1.8</target>
         </configuration>
       </plugin>
     </plugins>
diff --git a/modules/openapi-generator/src/main/resources/android/pom.mustache b/modules/openapi-generator/src/main/resources/android/pom.mustache
index d47c761c90af..2c6f72e4cf67 100644
--- a/modules/openapi-generator/src/main/resources/android/pom.mustache
+++ b/modules/openapi-generator/src/main/resources/android/pom.mustache
@@ -119,8 +119,8 @@
                 <artifactId>maven-compiler-plugin</artifactId>
                 <version>3.6.1</version>
                 <configuration>
-                    <source>{{#java8}}1.8{{/java8}}{{^java8}}1.7{{/java8}}</source>
-                    <target>{{#java8}}1.8{{/java8}}{{^java8}}1.7{{/java8}}</target>
+                    <source>1.8</source>
+                    <target>1.8</target>
                 </configuration>
             </plugin>
         </plugins>
diff --git a/samples/client/petstore/android/httpclient/.openapi-generator/VERSION b/samples/client/petstore/android/httpclient/.openapi-generator/VERSION
index 6555596f9311..5f68295fc196 100644
--- a/samples/client/petstore/android/httpclient/.openapi-generator/VERSION
+++ b/samples/client/petstore/android/httpclient/.openapi-generator/VERSION
@@ -1 +1 @@
-5.2.0-SNAPSHOT
\ No newline at end of file
+6.0.0-SNAPSHOT
\ No newline at end of file
diff --git a/samples/client/petstore/android/httpclient/build.gradle b/samples/client/petstore/android/httpclient/build.gradle
index 5f4c815d2ed1..4d2c18d82274 100644
--- a/samples/client/petstore/android/httpclient/build.gradle
+++ b/samples/client/petstore/android/httpclient/build.gradle
@@ -31,8 +31,8 @@ android {
         targetSdkVersion 25
     }
     compileOptions {
-        sourceCompatibility JavaVersion.VERSION_1_7
-        targetCompatibility JavaVersion.VERSION_1_7
+        sourceCompatibility JavaVersion.VERSION_1_8
+        targetCompatibility JavaVersion.VERSION_1_8
     }
 
     // Rename the aar correctly
diff --git a/samples/client/petstore/android/httpclient/git_push.sh b/samples/client/petstore/android/httpclient/git_push.sh
index ced3be2b0c7b..f53a75d4fabe 100644
--- a/samples/client/petstore/android/httpclient/git_push.sh
+++ b/samples/client/petstore/android/httpclient/git_push.sh
@@ -1,7 +1,7 @@
 #!/bin/sh
 # ref: https://help.github.com/articles/adding-an-existing-project-to-github-using-the-command-line/
 #
-# Usage example: /bin/sh ./git_push.sh wing328 openapi-pestore-perl "minor update" "gitlab.com"
+# Usage example: /bin/sh ./git_push.sh wing328 openapi-petstore-perl "minor update" "gitlab.com"
 
 git_user_id=$1
 git_repo_id=$2
@@ -38,14 +38,14 @@ git add .
 git commit -m "$release_note"
 
 # Sets the new remote
-git_remote=`git remote`
+git_remote=$(git remote)
 if [ "$git_remote" = "" ]; then # git remote not defined
 
     if [ "$GIT_TOKEN" = "" ]; then
         echo "[INFO] \$GIT_TOKEN (environment variable) is not set. Using the git credential in your environment."
         git remote add origin https://${git_host}/${git_user_id}/${git_repo_id}.git
     else
-        git remote add origin https://${git_user_id}:${GIT_TOKEN}@${git_host}/${git_user_id}/${git_repo_id}.git
+        git remote add origin https://${git_user_id}:"${GIT_TOKEN}"@${git_host}/${git_user_id}/${git_repo_id}.git
     fi
 
 fi
@@ -55,4 +55,3 @@ git pull origin master
 # Pushes (Forces) the changes in the local repository up to the remote repository
 echo "Git pushing to https://${git_host}/${git_user_id}/${git_repo_id}.git"
 git push origin master 2>&1 | grep -v 'To https'
-
diff --git a/samples/client/petstore/android/httpclient/pom.xml b/samples/client/petstore/android/httpclient/pom.xml
index f8718b1782cc..179c040e510c 100644
--- a/samples/client/petstore/android/httpclient/pom.xml
+++ b/samples/client/petstore/android/httpclient/pom.xml
@@ -119,8 +119,8 @@
                 <artifactId>maven-compiler-plugin</artifactId>
                 <version>3.6.1</version>
                 <configuration>
-                    <source>1.7</source>
-                    <target>1.7</target>
+                    <source>1.8</source>
+                    <target>1.8</target>
                 </configuration>
             </plugin>
         </plugins>
diff --git a/samples/client/petstore/android/httpclient/src/main/java/org/openapitools/client/api/UserApi.java b/samples/client/petstore/android/httpclient/src/main/java/org/openapitools/client/api/UserApi.java
index c6a854dec579..f0cd2ee0e706 100644
--- a/samples/client/petstore/android/httpclient/src/main/java/org/openapitools/client/api/UserApi.java
+++ b/samples/client/petstore/android/httpclient/src/main/java/org/openapitools/client/api/UserApi.java
@@ -20,6 +20,7 @@
 
 import java.util.*;
 
+import java.util.Date;
 import java.util.*;
 import org.openapitools.client.model.User;
 
diff --git a/samples/client/petstore/android/volley/.openapi-generator/VERSION b/samples/client/petstore/android/volley/.openapi-generator/VERSION
index 6555596f9311..5f68295fc196 100644
--- a/samples/client/petstore/android/volley/.openapi-generator/VERSION
+++ b/samples/client/petstore/android/volley/.openapi-generator/VERSION
@@ -1 +1 @@
-5.2.0-SNAPSHOT
\ No newline at end of file
+6.0.0-SNAPSHOT
\ No newline at end of file
diff --git a/samples/client/petstore/android/volley/build.gradle b/samples/client/petstore/android/volley/build.gradle
index afa1d97884d8..15a6ef68d268 100644
--- a/samples/client/petstore/android/volley/build.gradle
+++ b/samples/client/petstore/android/volley/build.gradle
@@ -35,8 +35,8 @@ android {
         targetSdkVersion 25
     }
     compileOptions {
-        sourceCompatibility JavaVersion.VERSION_1_7
-        targetCompatibility JavaVersion.VERSION_1_7
+        sourceCompatibility JavaVersion.VERSION_1_8
+        targetCompatibility JavaVersion.VERSION_1_8
     }
     lintOptions {
         abortOnError false
diff --git a/samples/client/petstore/android/volley/git_push.sh b/samples/client/petstore/android/volley/git_push.sh
index ced3be2b0c7b..f53a75d4fabe 100644
--- a/samples/client/petstore/android/volley/git_push.sh
+++ b/samples/client/petstore/android/volley/git_push.sh
@@ -1,7 +1,7 @@
 #!/bin/sh
 # ref: https://help.github.com/articles/adding-an-existing-project-to-github-using-the-command-line/
 #
-# Usage example: /bin/sh ./git_push.sh wing328 openapi-pestore-perl "minor update" "gitlab.com"
+# Usage example: /bin/sh ./git_push.sh wing328 openapi-petstore-perl "minor update" "gitlab.com"
 
 git_user_id=$1
 git_repo_id=$2
@@ -38,14 +38,14 @@ git add .
 git commit -m "$release_note"
 
 # Sets the new remote
-git_remote=`git remote`
+git_remote=$(git remote)
 if [ "$git_remote" = "" ]; then # git remote not defined
 
     if [ "$GIT_TOKEN" = "" ]; then
         echo "[INFO] \$GIT_TOKEN (environment variable) is not set. Using the git credential in your environment."
         git remote add origin https://${git_host}/${git_user_id}/${git_repo_id}.git
     else
-        git remote add origin https://${git_user_id}:${GIT_TOKEN}@${git_host}/${git_user_id}/${git_repo_id}.git
+        git remote add origin https://${git_user_id}:"${GIT_TOKEN}"@${git_host}/${git_user_id}/${git_repo_id}.git
     fi
 
 fi
@@ -55,4 +55,3 @@ git pull origin master
 # Pushes (Forces) the changes in the local repository up to the remote repository
 echo "Git pushing to https://${git_host}/${git_user_id}/${git_repo_id}.git"
 git push origin master 2>&1 | grep -v 'To https'
-
diff --git a/samples/client/petstore/android/volley/pom.xml b/samples/client/petstore/android/volley/pom.xml
index 98bff7edf8dd..53d3892bb62b 100644
--- a/samples/client/petstore/android/volley/pom.xml
+++ b/samples/client/petstore/android/volley/pom.xml
@@ -45,8 +45,8 @@
         <artifactId>maven-compiler-plugin</artifactId>
         <version>3.8.1</version>
         <configuration>
-          <source>1.7</source>
-          <target>1.7</target>
+          <source>1.8</source>
+          <target>1.8</target>
         </configuration>
       </plugin>
     </plugins>
diff --git a/samples/client/petstore/android/volley/src/main/java/org/openapitools/client/api/UserApi.java b/samples/client/petstore/android/volley/src/main/java/org/openapitools/client/api/UserApi.java
index edec8bce95e9..8baf3c9367aa 100644
--- a/samples/client/petstore/android/volley/src/main/java/org/openapitools/client/api/UserApi.java
+++ b/samples/client/petstore/android/volley/src/main/java/org/openapitools/client/api/UserApi.java
@@ -23,6 +23,7 @@
 import com.android.volley.Response;
 import com.android.volley.VolleyError;
 
+import java.util.Date;
 import java.util.*;
 import org.openapitools.client.model.User;