Refactor petstore tests and refresh build setup

checkstyle.xml

@@ -0,0 +1,34 @@
+<?xml version="1.0"?>
+<!DOCTYPE module PUBLIC
+        "-//Checkstyle//DTD Checkstyle Configuration 1.3//EN"
+        "https://checkstyle.org/dtds/configuration_1_3.dtd">
+
+<module name="Checker">
+    <property name="charset" value="UTF-8"/>
+    <property name="severity" value="error"/>
+
+    <module name="FileTabCharacter"/>
+
+    <module name="LineLength">
+        <property name="max" value="120"/>
+    </module>
+
+    <module name="TreeWalker">
+        <module name="TypeName"/>
+        <module name="MethodName"/>
+        <module name="ParameterName"/>
+        <module name="LocalVariableName"/>
+        <module name="MemberName"/>
+
+        <module name="AvoidStarImport"/>
+        <module name="UnusedImports"/>
+        <module name="RedundantImport"/>
+
+        <module name="NeedBraces"/>
+
+        <module name="WhitespaceAround"/>
+        <module name="WhitespaceAfter"/>
+
+        <module name="EmptyBlock"/>
+    </module>
+</module>