checkstyles to replicate the FIXME and ASCII character checks.

build.gradle

@@ -3,6 +3,7 @@
 plugins {
     id "com.github.johnrengelman.shadow"
     id "java"
+    id 'checkstyle'
 }
 
 Properties props = new Properties()

config/checkstyle/checkstyle.xml

@@ -0,0 +1,59 @@
+<?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">
+    <module name="SuppressWarningsFilter"/>
+
+    <property name="charset" value="UTF-8"/>
+
+    <property name="severity" value="warning"/>
+
+    <property name="fileExtensions" value="java"/>
+    <!-- Excludes all 'module-info.java' files              -->
+    <!-- See https://checkstyle.org/config_filefilters.html -->
+    <module name="BeforeExecutionExclusionFileFilter">
+        <property name="fileNamePattern" value="module\-info\.java$"/>
+    </module>
+    <!-- https://checkstyle.org/config_filters.html#SuppressionFilter -->
+    <module name="SuppressionFilter">
+        <property name="file" value="${org.checkstyle.google.suppressionfilter.config}"
+                  default="checkstyle-suppressions.xml" />
+        <property name="optional" value="true"/>
+    </module>
+
+    <!-- Checks for whitespace                               -->
+    <!-- See http://checkstyle.org/config_whitespace.html -->
+<!--    <module name="FileTabCharacter">-->
+<!--        <property name="eachLine" value="true"/>-->
+<!--    </module>-->
+
+<!--    <module name="LineLength">-->
+<!--        <property name="fileExtensions" value="java"/>-->
+<!--        <property name="max" value="100"/>-->
+<!--        <property name="ignorePattern" value="^package.*|^import.*|a href|href|http://|https://|ftp://"/>-->
+<!--    </module>-->
+
+    <module name="TreeWalker">
+        <module name="Regexp">
+            <property name="format" value="(FIXME|TODO:.*CRITICAL)"/>
+<!--            <property name="illegalPattern" value="true"/>-->
+            <property name="message"
+                      value="CRITICAL TODOs exist in project."/>
+        </module>
+        <module name="Regexp">
+            <property name="format" value="\P{ASCII}"/>
+<!--            <property name="illegalPattern" value="true"/>-->
+            <property name="message"
+                      value="Non-ASCII characters exist in project."/>
+        </module>
+        <module name="IllegalTokenText">
+            <property name="tokens" value="STRING_LITERAL, CHAR_LITERAL"/>
+            <property name="format"
+                      value="\\u00(09|0(a|A)|0(c|C)|0(d|D)|22|27|5(C|c))|\\(0(10|11|12|14|15|42|47)|134)"/>
+            <property name="message"
+                      value="Consider using special escape sequence instead of octal value or Unicode escaped value."/>
+        </module>
+    </module>
+</module>

core/build.gradle

@@ -2,6 +2,7 @@ plugins {
     id "com.github.johnrengelman.shadow"
     id 'java'
     id 'com.adarshr.test-logger' version '3.2.0'
+    id 'checkstyle'
 }
 
 group 'net.sf.openrocket'
@@ -18,11 +19,10 @@ repositories {
     mavenCentral()
 }
 
-//test {
+checkstyle {
-//    testLogging {
+    ignoreFailures = false
-//        events "PASSED", "SKIPPED", "FAILED"
+    maxWarnings = 0
-//    }
+}
-//}
 
 dependencies {
     implementation group: 'org.commonmark', name: 'commonmark', version: '0.19.0' // 0.21.0

swing/build.gradle

@@ -2,6 +2,7 @@ plugins {
     id "com.github.johnrengelman.shadow"
     id 'java'
     id 'com.adarshr.test-logger' version '3.2.0'
+    id 'checkstyle'
 }
 
 group 'net.sf.openrocket'
@@ -18,11 +19,10 @@ repositories {
     mavenCentral()
 }
 
-//test {
+checkstyle {
-//    testLogging {
+    ignoreFailures = false
-//        events "PASSED", "SKIPPED", "FAILED"
+    maxWarnings = 0
-//    }
+}
-//}
 
 configurations {
     testArtifactsClasspath {