Make JBakeConfiguration.addConfiguration() values take precedence

This closes jbake-org#717

jbake-core/src/main/java/org/jbake/app/configuration/DefaultJBakeConfiguration.java

@@ -690,7 +690,7 @@ public List<Property> getJbakeProperties() {
 
     @Override
     public void addConfiguration(Properties properties) {
-        compositeConfiguration.addConfiguration(new MapConfiguration(properties));
+        compositeConfiguration.addConfigurationFirst(new MapConfiguration(properties));
     }
 
     @Override

jbake-core/src/main/java/org/jbake/app/configuration/JBakeConfiguration.java

@@ -339,7 +339,7 @@ public interface JBakeConfiguration {
     String getVersion();
 
     /**
-     * Set a property value for the given key
+     * Set a property value for the given key.
      *
      * @param key   the key for the property
      * @param value the value of the property
@@ -371,6 +371,10 @@ public interface JBakeConfiguration {
 
     List<Property> getJbakeProperties();
 
+    /**
+     * Adds another configuration whose properties take precedence over the ones already set.
+     * @param properties
+     */
     void addConfiguration(Properties properties);
 }
 

jbake-core/src/test/java/org/jbake/app/configuration/DefaultJBakeConfigurationTest.java

@@ -0,0 +1,41 @@
+package org.jbake.app.configuration;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.io.File;
+import java.util.Properties;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
+
+public class DefaultJBakeConfigurationTest {
+
+    @TempDir
+    File root;
+
+    private JBakeConfiguration jBakeConfig;
+
+    @BeforeEach
+    public void setup() {
+        jBakeConfig = new ConfigUtil().loadConfig(root, null);
+    }
+
+    @Test
+    public void testAddConfiguration() {
+        Properties props = new Properties();
+        props.setProperty("version", "overwritten"); // overwrite property from default.properties
+        props.setProperty("foo", "bar");
+        jBakeConfig.addConfiguration(props);
+        assertEquals("overwritten", jBakeConfig.get("version"));
+        assertEquals("bar", jBakeConfig.get("foo"));
+    }
+
+    @Test
+    public void testSetProperty() {
+        jBakeConfig.setProperty("version", "overwritten"); // overwrite property from default.properties
+        jBakeConfig.setProperty("foo", "bar");
+        assertEquals("overwritten", jBakeConfig.get("version"));
+        assertEquals("bar", jBakeConfig.get("foo"));
+    }
+}