Apply necessary changes for java 8

bindings/java/src/main/java/org/github/tursodatabase/LimboConnection.java

@@ -46,7 +46,7 @@ public abstract class LimboConnection implements Connection {
     }
 
     private static AbstractDB open(String url, String fileName, Properties properties) throws SQLException {
-        if (fileName.isBlank()) {
+        if (fileName.isEmpty()) {
             throw new IllegalArgumentException("fileName should not be empty");
         }
 

bindings/java/src/main/java/org/github/tursodatabase/jdbc4/JDBC4Connection.java

@@ -4,6 +4,7 @@ import org.github.tursodatabase.LimboConnection;
 import org.github.tursodatabase.annotations.SkipNullableCheck;
 
 import java.sql.*;
+import java.util.HashMap;
 import java.util.Map;
 import java.util.Properties;
 import java.util.concurrent.Executor;
@@ -150,7 +151,7 @@ public class JDBC4Connection extends LimboConnection {
     @Override
     public Map<String, Class<?>> getTypeMap() throws SQLException {
         // TODO
-        return Map.of();
+        return new HashMap<>();
     }
 
     @Override