Issue checkstyle#12409: Inconsistent allowedAbbreviations

src/main/java/com/puppycrawl/tools/checkstyle/checks/naming/AbbreviationAsWordInNameCheck.java

@@ -583,7 +583,7 @@ private String getDisallowedAbbreviation(String str) {
             else if (abbrStarted) {
                 abbrStarted = false;
 
-                final int endIndex = index - 1;
+                final int endIndex = Character.isLetterOrDigit(symbol) ? index-1 : index;
                 result = getAbbreviationIfIllegal(str, beginIndex, endIndex);
                 if (result != null) {
                     break;

src/test/java/com/puppycrawl/tools/checkstyle/checks/naming/AbbreviationAsWordInNameCheckTest.java

@@ -467,4 +467,13 @@ public void testReceiver() throws Exception {
                 expected);
     }
 
+    @Test
+    public void demoTest() throws Exception {
+        final String[] expected = CommonUtil.EMPTY_STRING_ARRAY;
+
+        verifyWithInlineConfigParser(
+                getPath("InputAbbreviationAsWordInNameType7.java"),
+                expected);
+    }
+
 }

src/test/resources/com/puppycrawl/tools/checkstyle/checks/naming/abbreviationaswordinname/InputAbbreviationAsWordInNameType7.java

@@ -0,0 +1,28 @@
+/*
+AbbreviationAsWordInName
+allowedAbbreviations = ORDER, OBSERVATION, UNDERSCORE, TEST
+
+
+*/
+
+
+package com.puppycrawl.tools.checkstyle.checks.naming.abbreviationaswordinname;
+
+public class InputAbbreviationAsWordInNameType7 {
+    void getTEST() {
+    }
+
+    void getORDER_OBSERVATION() {}
+
+    void getUNDERSCORE() {}
+
+    void getTEST_OBSERVATION() {}
+
+    void getTEST_UNDERSCORE() {}
+
+    void getORDER() {}
+
+    void getOBSERVATION() {}
+
+    void getORDER_UNDERSCORE() {}
+}