Fail build when checkstyle fails (#1027)

Fail build when checkstyle fails.

examples/pom.xml

diff --git a/examples/pom.xml b/examples/pom.xml
index 85825ec..a525782 100644
--- a/examples/pom.xml
+++ b/examples/pom.xml
@@ -173,6 +173,7 @@
                         <outputDirectory>${project.build.directory}/checkstyle</outputDirectory>
                         <outputFile>${project.build.directory}/checkstyle/checkstyle-result.xml</outputFile>
                         <configLocation>${basedir}/../etc/config/checkstyle.xml</configLocation>
+                        <failsOnError>true</failsOnError>
                     </configuration>
                     <dependencies>
                         <dependency>

jaxrs-api/pom.xml

diff --git a/jaxrs-api/pom.xml b/jaxrs-api/pom.xml
index ee4ac50..d1ab5c2 100644
--- a/jaxrs-api/pom.xml
+++ b/jaxrs-api/pom.xml
@@ -424,6 +424,7 @@
                         <outputFile>${project.build.directory}/checkstyle/checkstyle-result.xml</outputFile>
                         <configLocation>${basedir}/../etc/config/checkstyle.xml</configLocation>
                         <excludes>**/module-info.java</excludes>
+                        <failsOnError>true</failsOnError>
                     </configuration>
                     <dependencies>
                         <dependency>