Proxy messages written to log that cannot be satisfied

Using the `org.eclipse.core.net`and `org.eclipse.ui.net` bundles in Eclipse or in an RCP application if proxy settings are set in Preferences each time there are messages such as:

```
!MESSAGE System property https.proxyHost is not set but should be 192.168.1.10.
!MESSAGE System property https.proxyPort is not set but should be 3128.
!MESSAGE System property https.proxyHost is not set but should be 192.168.1.10.
!MESSAGE System property https.proxyPort is not set but should be 3128.
```

I've traced this to a check the code does here:

https://github.com/eclipse-platform/eclipse.platform/blob/master/team/bundles/org.eclipse.core.net/src/org/eclipse/core/internal/net/ProxyType.java

I've tried setting these system properties manually but then get different messages (even if the system has proxy settings):

```
!MESSAGE The HTTP proxy is enabled in the preferences but disabled in the system settings
!MESSAGE The SSL proxy is enabled in the preferences but disabled in the system settings
!MESSAGE The SSL proxy is enabled in the preferences but disabled in the system settings
```

So how does one satisfy these requirements?

Iniziare da team/bundles/org.eclipse.core.net/src/org/eclipse/core/internal/net/ProxyType.java e verificare come le preferenze proxy di org.eclipse.core.net e org.eclipse.ui.net vengano confrontate con le proprietà di sistema https.proxyHost e https.proxyPort. Riprodurre i messaggi registrati con le impostazioni proxy abilitate, quindi determinare la gestione prevista della discrepanza tra le preferenze e le impostazioni di sistema; il lavoro è completato quando la configurazione proxy non produce più messaggi impossibili da soddisfare o fuorvianti.

Scritto dal modello di indicizzazione a partire dal testo della issue.