use possesive quantifier

src/main/java/org/cryptomator/frontend/fuse/mount/AbstractMountBuilder.java

@@ -29,9 +29,10 @@ public MountBuilder setMountpoint(Path mountPoint) {
 
 	@Override
 	public MountBuilder setMountFlags(String mountFlagsString) {
+		var mfs = " "+mountFlagsString.trim();
 		// we assume that each flag starts with "-"
 		var notEmpty = Predicate.not(String::isBlank);
-		this.mountFlags = Pattern.compile("\\s+-").splitAsStream(" "+mountFlagsString).filter(notEmpty).map("-"::concat).collect(Collectors.toUnmodifiableSet());
+		this.mountFlags = Pattern.compile("\\s++-").splitAsStream(mfs).filter(notEmpty).map("-"::concat).collect(Collectors.toUnmodifiableSet());
 		return this;
 	}
 

src/test/java/org/cryptomator/frontend/fuse/mount/AbstractMountBuilderTest.java

@@ -0,0 +1,45 @@
+package org.cryptomator.frontend.fuse.mount;
+
+import org.cryptomator.integrations.mount.Mount;
+import org.cryptomator.integrations.mount.MountFailedException;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.CsvSource;
+
+import java.nio.file.Path;
+import java.util.Arrays;
+
+public class AbstractMountBuilderTest {
+
+	TestMountBuilder inTest = new TestMountBuilder();
+
+	@ParameterizedTest
+	@CsvSource(textBlock = """
+			-asd,-asd
+			-asd\t-qwe,-asd;-qwe
+			 -asd ,-asd
+			-abc qwe,-abc qwe
+			\t -foo file/to/use -bar 4 -b  az not,-foo file/to/use;-bar 4;-b  az not
+			""")
+	public void testSetMountFlags(String toTest, String expectedRaw) {
+		var expected = Arrays.stream(expectedRaw.split(";"));
+
+		inTest.setMountFlags(toTest);
+		expected.forEach( exp -> Assertions.assertTrue(inTest.mountFlags.contains(exp)));
+	}
+
+
+	class TestMountBuilder extends AbstractMountBuilder {
+
+		public TestMountBuilder() {
+			super(Path.of("abc"));
+		}
+
+		@Override
+		public Mount mount() throws MountFailedException {
+			return null;
+		}
+	}
+}