MYFACES-4731 (DISABLE_OPTIONAL_EL_RESOLVER)

impl/src/main/java/org/apache/myfaces/config/webparameters/MyfacesConfig.java

@@ -790,6 +790,13 @@ public class MyfacesConfig
     public static final String EXCEPTION_TYPES_TO_IGNORE_IN_LOGGING =
             "org.apache.myfaces.EXCEPTION_TYPES_TO_IGNORE_IN_LOGGING";
 
+    /**
+     * Expression Language 6.0's OptionalELResolver is enabled by default, so this option allows us to disable it.
+     */
+    @JSFWebConfigParam(name="org.apache.myfaces.DISABLE_OPTIONAL_EL_RESOLVER", since="4.1.2", defaultValue = "false")
+    public static final String DISABLE_OPTIONAL_EL_RESOLVER = "org.apache.myfaces.DISABLE_OPTIONAL_EL_RESOLVER";
+    public static final boolean DISABLE_OPTIONAL_EL_RESOLVER_DEFAULT = false;
+
     // we need it, applicationImpl not ready probably
     private ProjectStage projectStage = ProjectStage.Production;
     private boolean strictJsf2AllowSlashLibraryName;
@@ -870,7 +877,8 @@ public class MyfacesConfig
     private boolean elResolverTracing = EL_RESOLVER_TRACING_DEFAULT;
     private long faceletsRefreshPeriod = -1;
     private List<String> exceptionTypesToIgnoreInLogging = new ArrayList<>();
-
+    private boolean disableOptionalResolver = DISABLE_OPTIONAL_EL_RESOLVER_DEFAULT;
+
     private static final boolean MYFACES_IMPL_AVAILABLE;
     private static final boolean RI_IMPL_AVAILABLE;
 
@@ -1345,6 +1353,9 @@ else if (refreshTransientBuildOnPSS.equalsIgnoreCase("true") ||
                 cfg.exceptionTypesToIgnoreInLogging.add(exceptionTypeToIgnoreInLogging);
             }
         }
+
+        cfg.disableOptionalResolver
+                = getBoolean(extCtx, DISABLE_OPTIONAL_EL_RESOLVER, DISABLE_OPTIONAL_EL_RESOLVER_DEFAULT);
 
         return cfg;
     }
@@ -1815,5 +1826,10 @@ public List<String> getExceptionTypesToIgnoreInLogging()
     {
         return exceptionTypesToIgnoreInLogging;
     }
+
+    public boolean isOptionalELResolverDisabled()
+    {
+        return disableOptionalResolver;
+    }
 }
 

impl/src/main/java/org/apache/myfaces/el/DefaultELResolverBuilder.java

@@ -157,7 +157,10 @@ public void build(FacesContext facesContext, CompositeELResolver compositeElReso
         {
             try
             {
-                list.add(new OptionalELResolver());
+                if(!config.isOptionalELResolverDisabled()) 
+                {
+                    list.add(new OptionalELResolver()); // not disabled (default), so add it in.
+                }
                 list.add(new RecordELResolver());
             }
             catch (Throwable ex)