fixes on adding printers

unique printers were not ignored

META-INF/MANIFEST.MF

@@ -2,7 +2,7 @@ Manifest-Version: 1.0
 Bundle-ManifestVersion: 2
 Bundle-Name: beluga.serverprint
 Bundle-SymbolicName: beluga.serverprint
-Bundle-Version: 5.0.0.qualifier
+Bundle-Version: 5.1.0.qualifier
 Service-Component: OSGI-INF/*.xml
 Bundle-RequiredExecutionEnvironment: JavaSE-11
 Require-Bundle: org.adempiere.base;bundle-version="5.1.0",

src/de/schoenbeck/serverprint/model/MPrinterProvider.java

@@ -32,8 +32,8 @@ public MPrinterProvider(Properties ctx, ResultSet rs, String trxName) {
 	}
 
 	public List<MPrinter> getKnownPrinters() {
-		final String sql = "SELECT * FROM " + MPrinter.Table_Name
-						+ " WHERE " + MPrinterProvider.Table_Name + " = ?";
+		final String sql = "SELECT DISTINCT * FROM " + MPrinter.Table_Name
+						+ " WHERE " + MPrinter.COLUMNNAME_sbsp_printerprovider_ID + " = ?";
 		LinkedList<MPrinter> rtn = new LinkedList<>();
 
 		PreparedStatement ps = null;

src/de/schoenbeck/serverprint/printProvider/ServerPrintPrinterLookupProcess.java

@@ -25,13 +25,14 @@ protected String doIt() throws Exception {
 				.orElseThrow( () -> new NoSuchElementException("The provider does not exist.") );
 		var printers = lookupProcess.getAvailablePrinters(record_id, get_TrxName());
 
-		var knownPrinters = new HashSet<Integer>();
-		for (int i : provider.getKnownPrinterIDs())
-			knownPrinters.add(i);
+		HashSet<MPrinter> knownPrinters = new HashSet<>(provider.getKnownPrinters());
 
+		outerloop:
 		for (MPrinter p : printers) {
-			if (!knownPrinters.contains(p.get_ID()))
-				p.save();
+			for (var k : knownPrinters)
+				if (p.getValue().equals(k.getValue()))
+					break outerloop;
+			p.save();
 		}
 
 		//TODO: optionally show printers to user and let them select, which to keep