Merge pull request #914 from mP1/feature/ExpressionFunction-NO_PARAMETERS

ExpressionFunction.NO_PARAMETERS

Author: mP1

src/main/java/walkingkooka/tree/expression/function/ExpressionFunction.java

@@ -76,6 +76,11 @@ default ExpressionFunction<T, C> setName(final Optional<ExpressionFunctionName>
         return ExpressionFunctionCustomName.with(this, name);
     }
 
+    /**
+     * Constant useful when a function expects no parameters.
+     */
+    List<ExpressionFunctionParameter<?>> NO_PARAMETERS = Lists.empty();
+
     /**
      * Returns meta info about the parameters for this function.
      */