Apply the Jetbrains Pattern annotation to the QosReason ctor (#932)

Apply the Jetbrains Pattern annotation to the QosReason ctor

Author: Carter Kozak

changelog/@unreleased/pr-932.v2.yml

@@ -0,0 +1,5 @@
+type: improvement
+improvement:
+  description: Apply the Jetbrains Pattern annotation to the QosReason ctor
+  links:
+  - https://github.com/palantir/conjure-java-runtime-api/pull/932

errors/build.gradle

@@ -7,6 +7,7 @@ dependencies {
     api "com.fasterxml.jackson.core:jackson-databind"
     api "com.google.code.findbugs:jsr305"
     api "com.palantir.safe-logging:safe-logging"
+    api "org.jetbrains:annotations"
     implementation "com.palantir.safe-logging:preconditions"
 
     testImplementation project(":extras:jackson-support")

errors/src/main/java/com/palantir/conjure/java/api/errors/QosReason.java

@@ -35,13 +35,15 @@ public final class QosReason {
     @CompileTimeConstant
     private final String reason;
 
-    private static final Pattern PATTERN = Pattern.compile("^[a-z0-9\\-]{1,50}$");
+    private static final String PATTERN_STRING = "^[a-z0-9\\-]{1,50}$";
+    private static final Pattern PATTERN = Pattern.compile(PATTERN_STRING);
 
     private QosReason(@CompileTimeConstant String reason) {
         this.reason = reason;
     }
 
-    public static QosReason of(@CompileTimeConstant String reason) {
+    public static QosReason of(
+            @CompileTimeConstant @org.intellij.lang.annotations.Pattern(PATTERN_STRING) String reason) {
         Preconditions.checkArgument(
                 PATTERN.matcher(reason).matches(),
                 "Reason must be at most 50 characters, and only contain lowercase letters, numbers, "