SONARJAVA-6099 Fix FP on S1135 due to off-by-one error (#5438)

Author: tomasz-tylenda-sonarsource

java-checks-test-sources/default/src/main/java/checks/TodoTagPresenceCheckSample.java

@@ -27,6 +27,8 @@
  // Noncompliant@+1
 //// TODO Explanation
 
+// Spanish todos
+
 // PreTodo
 // toDomain
 package checks;

java-checks/src/main/java/org/sonar/java/checks/CommentContainsPatternChecker.java

@@ -38,7 +38,7 @@ private static boolean isLetterAround(String line, String pattern) {
     int end = start + pattern.length();
 
     boolean pre = start > 0 && Character.isLetter(line.charAt(start - 1));
-    boolean post = end < line.length() - 1 && Character.isLetter(line.charAt(end));
+    boolean post = end < line.length() && Character.isLetter(line.charAt(end));
 
     return pre || post;
   }