fix(PW-3126): fix DN to BIC extraction to include branch from ou component

Added parseBranch() to DistinguishedName to extract the branch code from
the ou field of a SWIFT DN string, selecting the rightmost ou when multiple
are present (closest to o=<bic8>).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: zubri

CHANGELOG.md

@@ -1,5 +1,8 @@
 # Prowide Core - CHANGELOG
 
+#### 10.3.9 - SNAPSHOT
+  * (PW-3126) Fixed DN to BIC extraction in `DistinguishedName` to include the branch code from the `ou` component
+
 #### 10.3.8 - January 2026
   * (PW-2967) Fixed Field95D component label from "Legal Entity Identifier" to "Digital Ledger Identifier" to match XSD schema
   * Feat: `MtSwiftMessage` now automatically extracts and persists UETR from block 3 field 121 during message parsing

src/main/java/com/prowidesoftware/swift/model/DistinguishedName.java

@@ -1,6 +1,7 @@
 package com.prowidesoftware.swift.model;
 
 import org.apache.commons.lang3.StringUtils;
+import org.apache.commons.lang3.Strings;
 
 /**
  * Represents a Distinguished Name (DN) in the context of a directory service.
@@ -62,13 +63,38 @@ public static String parseBIC(final String dn) {
             return null;
         }
         for (String s : StringUtils.split(dn, ",")) {
-            if (StringUtils.startsWith(s, "o=") && !StringUtils.equals(s, "o=swift")) {
+            if (Strings.CS.startsWith(s, "o=") && !Strings.CS.equals(s, "o=swift")) {
                 return StringUtils.upperCase(StringUtils.substringAfter(s, "o="));
             }
         }
         return null;
     }
 
+    /**
+     * Parses the branch code from a SWIFT Distinguished Name string.
+     *
+     * <p>The branch is represented by the {@code ou} component. When multiple {@code ou} components
+     * are present, the one closest to {@code o=&lt;bic8&gt;} (i.e. the rightmost) is the branch code,
+     * as DNs are read right-to-left from least to most specific:
+     * <pre>cn=a,ou=dept,ou=bbb,o=biccode,o=swift → branch is "BBB"</pre>
+     *
+     * @param dn the Distinguished Name string, may be null or blank
+     * @return the branch code in uppercase, or null if not present or if the input is blank
+     */
+    protected static String parseBranch(final String dn) {
+        if (StringUtils.isBlank(dn)) {
+            return null;
+        }
+        String branch = null;
+        for (String s : StringUtils.split(dn, ",")) {
+            if (Strings.CS.startsWith(s, "ou=")) {
+                // keep iterating — last match is the rightmost (closest to o=<bic8>)
+                branch = StringUtils.substringAfter(s, "ou=");
+            }
+        }
+        return StringUtils.isBlank(branch) ? null : StringUtils.upperCase(branch);
+    }
+
     /**
      * Builder class for constructing DistinguishedName instances.
      */

src/test/java/com/prowidesoftware/swift/model/DistinguishedNameTest.java

@@ -57,4 +57,46 @@ void testParseBIC() {
 
         assertNull(DistinguishedName.parseBIC("XXX"));
     }
+
+    @Test
+    void testParseBranchSingleOU() {
+        assertEquals("XXX", DistinguishedName.parseBranch("ou=xxx,o=biccode,o=swift"));
+    }
+
+    @Test
+    void testParseBranchUppercasesResult() {
+        assertEquals("XXX", DistinguishedName.parseBranch("ou=XXX,o=biccode,o=swift"));
+    }
+
+    @Test
+    void testParseBranchWithCN() {
+        assertEquals("XXX", DistinguishedName.parseBranch("cn=a,ou=xxx,o=biccode,o=swift"));
+    }
+
+    @Test
+    void testParseBranchMultipleOU() {
+        // rightmost ou (closest to o=<bic8>) is the branch; leftmost is a subdivision
+        assertEquals("BBB", DistinguishedName.parseBranch("cn=a,ou=dept,ou=bbb,o=biccode,o=swift"));
+    }
+
+    @Test
+    void testParseBranchNoOU() {
+        assertNull(DistinguishedName.parseBranch("o=biccode,o=swift"));
+    }
+
+    @Test
+    void testParseBranchNull() {
+        assertNull(DistinguishedName.parseBranch(null));
+    }
+
+    @Test
+    void testParseBranchBlank() {
+        assertNull(DistinguishedName.parseBranch(""));
+        assertNull(DistinguishedName.parseBranch("   "));
+    }
+
+    @Test
+    void testParseBranchNoMatch() {
+        assertNull(DistinguishedName.parseBranch("o=biccode,o=swift"));
+    }
 }