[feature] Add missing #toString() method to ExtensionExpression to aid in debugging

Author: adamretter

exist-core/src/main/java/org/exist/xquery/ExtensionExpression.java

@@ -178,4 +178,21 @@ public void resetState(final boolean postOptimization) {
     public void accept(final ExpressionVisitor visitor) {
         visitor.visit(innerExpression);
     }
+
+    @Override
+    public String toString() {
+        final StringBuilder result = new StringBuilder();
+
+        if (pragmas != null) {
+            for (final Pragma pragma : pragmas) {
+                result.append(pragma.toString());
+            }
+        }
+
+        result.append("{ ");
+        result.append(innerExpression.toString());
+        result.append(" }");
+
+        return result.toString();
+    }
 }