ENH: Added null constructor to phasePropertiesList

src/lagrangian/intermediate/phaseProperties/phasePropertiesList/phasePropertiesList.C

@@ -27,6 +27,14 @@ License
 
 // * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
 
+Foam::phasePropertiesList::phasePropertiesList()
+:
+    props_(),
+    phaseTypeNames_(),
+    stateLabels_()
+{}
+
+
 Foam::phasePropertiesList::phasePropertiesList
 (
     Istream& is,

src/lagrangian/intermediate/phaseProperties/phasePropertiesList/phasePropertiesList.H

@@ -65,14 +65,20 @@ class phasePropertiesList
 
 public:
 
-    //- Constructor
-    phasePropertiesList
-    (
-        Istream& is,
-        const wordList& gasNames,
-        const wordList& liquidNames,
-        const wordList& solidNames
-    );
+     // Constructors
+
+        //- Construct null
+        phasePropertiesList();
+
+        //- Construct from components
+        phasePropertiesList
+        (
+            Istream& is,
+            const wordList& gasNames,
+            const wordList& liquidNames,
+            const wordList& solidNames
+        );
+
 
     //- Destructor
     ~phasePropertiesList();