private int assertPresentAndGetIndex(String name) {
        int index = this.propertySourceList.indexOf(PropertySource.named(name));
        if (index == -1) {
            throw new IllegalArgumentException("PropertySource named '" + name + "' does not exist");
        }
        return index;
    }
private int assertPresentAndGetIndex ( String name ) { int index = this . propertySourceList . indexOf ( PropertySource . named ( name ) ) ; if ( index == - 1 ) { throw new IllegalArgumentException ( "PropertySource named '" + name + "' does not exist" ) ; } return index ; }
Assert that the named property source is present and return its index.

@param name {@linkplain PropertySource#getName() name of the property source}
to find
@throws IllegalArgumentException if the named property source is not present