Fix SpotBugs errors.

[ERROR] Medium: org.apache.commons.dbcp2.PStmtKey.getColumnNames() may
expose internal representation by returning PStmtKey.columnNames
[org.apache.commons.dbcp2.PStmtKey] At PStmtKey.java:[line 864]
EI_EXPOSE_REP
[ERROR] Medium: org.apache.commons.dbcp2.PoolingDriver.pools is a
mutable collection which should be package protected
[org.apache.commons.dbcp2.PoolingDriver] At PoolingDriver.java:[line 51]
MS_MUTABLE_COLLECTION_PK

src/changes/changes.xml

@@ -107,6 +107,12 @@ The <action> type attribute can be add,update,fix,remove.
       <action dev="ggregory" type="fix">
         org.apache.commons.dbcp2.managed.DataSourceXAConnectionFactory.setPassword(char[]) may expose internal representation by storing an externally mutable object into DataSourceXAConnectionFactory.userPassword.
       </action>
+      <action dev="ggregory" type="fix">
+        org.apache.commons.dbcp2.PStmtKey.getColumnIndexes() may expose internal representation by returning PStmtKey.columnIndexes.
+      </action>
+      <action dev="ggregory" type="fix">
+        org.apache.commons.dbcp2.PStmtKey.getColumnNames() may expose internal representation by returning PStmtKey.columnNames.
+      </action>
       <!-- UPDATES -->
       <action dev="ggregory" type="update" due-to="Dependabot">
         Bump mockito-core from 3.5.11 to 3.10.0 #66, #72, #77, #85, #91, #105.

src/main/java/org/apache/commons/dbcp2/PStmtKey.java

@@ -852,7 +852,7 @@ public String getCatalog() {
      * @return An array of column indexes.
      */
     public int[] getColumnIndexes() {
-        return columnIndexes;
+        return columnIndexes == null ? null : columnIndexes.clone();
     }
 
     /**
@@ -861,7 +861,7 @@ public int[] getColumnIndexes() {
      * @return An array of column names.
      */
     public String[] getColumnNames() {
-        return columnNames;
+        return columnNames == null ? null : columnNames.clone();
     }
 
     /**