public MapStoreConfig setClassName(@Nonnull String className) {
        this.className = checkHasText(className, "Map store class name must contain text");
        this.implementation = null;
        return this;
    }
@Test
    public void setClassName() {
        assertEquals("some.class", cfgNonNullClassName.getClassName());
        assertEquals(new MapStoreConfig().setClassName("some.class"), cfgNonNullClassName);
    }