[LANG-1802] Fix collision in CharRange.hashCode()

Author: garydgregory

src/changes/changes.xml

@@ -73,6 +73,7 @@ The <action> type attribute can be add,update,fix,remove.
     <action                   type="fix" dev="ggregory" due-to="David Du, Gary Gregory">Speed up StringUtils.getDigits(String) #1515.</action>
     <action                   type="fix" dev="ggregory" due-to="David Du, Gary Gregory">Remove redundant length check in StringUtils.isBlank(CharSequence) #1516.</action>
     <action issue="LANG-1800" type="fix" dev="ggregory" due-to="IcoreE">Incorrect grammar and unclear wording in RandomStringUtils#random method #1520.</action>
+    <action issue="LANG-1802" type="fix" dev="ggregory" due-to="Gary Gregory, IcoreE">Fix collision in CharRange.hashCode().</action>
     <!-- ADD -->
     <!-- UPDATE -->
     <action                   type="update" dev="ggregory" due-to="Gary Gregory, Dependabot">Bump org.apache.commons:commons-parent from 92 to 93 #1498.</action>

src/main/java/org/apache/commons/lang3/CharRange.java

@@ -314,7 +314,7 @@ public char getStart() {
      */
     @Override
     public int hashCode() {
-        return 83 + start + 7 * end + (negated ? 1 : 0);
+        return Objects.hash(end, negated, start);
     }
 
     /**

src/test/java/org/apache/commons/lang3/CharRangeTest.java

@@ -311,6 +311,21 @@ void testHashCode() {
         assertNotEquals(rangenotbf.hashCode(), rangeae.hashCode());
     }
 
+    /**
+     * Tests https://issues.apache.org/jira/browse/LANG-1802
+     */
+    @Test
+    void testHashCodeLang1802() {
+        // case A：hash=99
+        final CharRange a1 = CharRange.isNotIn((char) 1, (char) 2); // 1,2,true → 83+1+14+1=99
+        final CharRange a2 = CharRange.isIn((char) 2, (char) 2); // 2,2,false → 83+2+14+0=99
+        assertNotEquals(a1.hashCode(), a2.hashCode()); // Collision
+        // case B：hash=123
+        final CharRange b1 = CharRange.isIn((char) 5, (char) 5); // 5,5,false →83+5+35+0=123
+        final CharRange b2 = CharRange.isNotIn((char) 4, (char) 5); // 4,5,true →83+4+35+1=123
+        assertNotEquals(b1.hashCode(), b2.hashCode()); // Collision
+    }
+
     @Test
     void testIterator() {
         final CharRange a = CharRange.is('a');