Fix isSingleTokenString return

Signed-off-by: Arthit Suriyawongkul <arthit@gmail.com>

Author: bact

src/main/java/org/spdx/utility/compare/LicenseCompareHelper.java

@@ -27,6 +27,7 @@
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 import java.util.Collection;
+import javax.annotation.Nullable;
 
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -206,7 +207,7 @@ public static String locateOriginalText(String fullLicenseText, int startToken,
 	 *         or {@code null} if none is found.
 	 */
 	public static @Nullable String getFirstLicenseToken(@Nullable String text) {
-		if (text == null) {
+		if (text == null || text.isEmpty()) {
 			return null;
 		}
 		String textToTokenize = LicenseTextHelper.normalizeText(LicenseTextHelper.replaceMultWord(LicenseTextHelper.replaceSpaceComma(
@@ -233,7 +234,7 @@ public static String locateOriginalText(String fullLicenseText, int startToken,
 	 *         {@code false} otherwise.
 	 */
 	public static boolean isSingleTokenString(@Nullable String text) {
-		if (text == null) {
+		if (text == null || text.isEmpty()) {
 			return false;
 		}
 		if (text.contains("\n")) {
@@ -250,7 +251,7 @@ public static boolean isSingleTokenString(@Nullable String text) {
 				}
 			}
 		}
-		return true;
+		return found;
 	}
 
 	/**

src/test/java/org/spdx/utility/compare/LicenseCompareHelperTest.java

@@ -542,13 +542,18 @@ public void testLicenseEqualsNoneLicense() throws InvalidSPDXAnalysisException,
 	}
 
 	public void testisSingleTokenString() {
-		assertTrue(LicenseCompareHelper.isSingleTokenString(""));
+		assertTrue(LicenseCompareHelper.isSingleTokenString("token"));
 		assertTrue(LicenseCompareHelper.isSingleTokenString(" token "));
+		assertTrue(LicenseCompareHelper.isSingleTokenString(" \n token "));
 		assertTrue(LicenseCompareHelper.isSingleTokenString("'"));
 		assertTrue(LicenseCompareHelper.isSingleTokenString(" '"));
 		assertTrue(LicenseCompareHelper.isSingleTokenString("' "));
 		assertFalse(LicenseCompareHelper.isSingleTokenString("a and"));
 		assertFalse(LicenseCompareHelper.isSingleTokenString("a\nand"));
+		assertFalse(LicenseCompareHelper.isSingleTokenString("a and  "));
+		assertFalse(LicenseCompareHelper.isSingleTokenString("  a and"));
+		assertFalse(LicenseCompareHelper.isSingleTokenString("\n"));
+		assertFalse(LicenseCompareHelper.isSingleTokenString(""));
 		assertFalse(LicenseCompareHelper.isSingleTokenString(null));
 	}