Some examples have reference to wrong gradle-7.1.1-bin.zip file

Some of the examples have a gradle wrapper properties file that points to a non existing distributionUrl.

```
distributionUrl=https\://services.gradle.org/distributions/gradle-7.1.1bin.zip
```

should be 

```
distributionUrl=https\://services.gradle.org/distributions/gradle-7.1.1-bin.zip
```