[MNG-8388] Fix escape characters being replaced to change the original configuration (#1946)

* [MNG-8388] Fix escape characters being replaced to change the original configuration

Signed-off-by: crazyhzm <[email protected]>

* Add unit test

---------

Signed-off-by: crazyhzm <[email protected]>
Co-authored-by: Guillaume Nodet <[email protected]>

Author: CrazyHZM

impl/maven-impl/src/main/java/org/apache/maven/internal/impl/model/DefaultInterpolator.java

@@ -420,7 +420,7 @@ public static String unescape(@Nullable String val) {
         int escape = val.indexOf(ESCAPE_CHAR);
         while (escape >= 0 && escape < val.length() - 1) {
             char c = val.charAt(escape + 1);
-            if (c == '{' || c == '}' || c == ESCAPE_CHAR) {
+            if (c == '{' || c == '}') {
                 val = val.substring(0, escape) + val.substring(escape + 1);
             }
             escape = val.indexOf(ESCAPE_CHAR, escape + 1);

impl/maven-impl/src/test/java/org/apache/maven/internal/impl/model/DefaultInterpolatorTest.java

@@ -98,6 +98,7 @@ void testSubstitutionEscape() {
         assertEquals("${a}", substVars("$\\{a${#}\\}", "b"));
         assertEquals("${a}", substVars("$\\{a\\}${#}", "b"));
         assertEquals("${a}", substVars("$\\{a\\}", "b"));
+        assertEquals("\\\\", substVars("\\\\", "b"));
     }
 
     @Test