@Override
    public Attribute.Type getReturnType() {
        return returnType;
    }
Executor class for Siddhi cast function. Converts the given parameter according to the castTo parameter.
Incompatible arguments cause {@link ClassCastException} if further processed.
modules/siddhi-core/src/main/java/io/siddhi/core/executor/function/CastFunctionExecutor.java