API inconsistency in chaining .sqlResource()

**Citrus Version**
2.8.0

**Expected behavior**
Using chained `sqlResource()` configurations should execute all given parameters on its `String` and its `Resource` signature.

**Actual behavior**
- On the `Resource` signature, all given sql statements are executed
- On the `String` signature, only the last given resource file is executed.

**Test case sample**
Only `foobar.sql` is executed
```java
sql(action -> action.dataSource(dataSource)
.sqlResource("classpath:sql/foo.sql")
.sqlResource("classpath:sql/bar.sql")
.sqlResource("classpath:sql/foobar.sql")
);
```

All statements are executed
```java
sql(action -> action.dataSource(dataSource)
.sqlResource(new ClassPathResource("classpath:sql/foo.sql"))
.sqlResource(new ClassPathResource("classpath:sql/bar.sql"))
.sqlResource(new ClassPathResource("classpath:sql/foobar.sql"))
);
```