ResolveMerger: Allow setting the TreeWalk AttributesNodeProvider

When a merger is created without a Repository, no
AttributesNodeProvider is created in the TreeWalk. Since mergers are
often created with a custom ObjectInserter and no repo, they skip any
lookups of attributes from any of the gitattributes files (within a
tree, in the repo info/ dir, or user/global). Since there are
potentially merge-affecting attributes in those files, callers might
want to use both a custom ObjectInserter and an AttributesNodeProvider.

Change-Id: I7997309003bbb598e1002261b3be7f2cc52066c8

org.eclipse.jgit/.settings/.api_filters

diff --git a/org.eclipse.jgit/.settings/.api_filters b/org.eclipse.jgit/.settings/.api_filters
index 28b20ab..2c22f02 100644
--- a/org.eclipse.jgit/.settings/.api_filters
+++ b/org.eclipse.jgit/.settings/.api_filters
@@ -32,4 +32,24 @@
             </message_arguments>
         </filter>
     </resource>
+    <resource path="src/org/eclipse/jgit/merge/ResolveMerger.java" type="org.eclipse.jgit.merge.ResolveMerger">
+        <filter id="336658481">
+            <message_arguments>
+                <message_argument value="org.eclipse.jgit.merge.ResolveMerger"/>
+                <message_argument value="attributesNodeProvider"/>
+            </message_arguments>
+        </filter>
+        <filter id="1142947843">
+            <message_arguments>
+                <message_argument value="6.10.1"/>
+                <message_argument value="attributesNodeProvider"/>
+            </message_arguments>
+        </filter>
+        <filter id="1142947843">
+            <message_arguments>
+                <message_argument value="6.10.1"/>
+                <message_argument value="setAttributesNodeProvider(AttributesNodeProvider)"/>
+            </message_arguments>
+        </filter>
+    </resource>
 </component>

org.eclipse.jgit/src/org/eclipse/jgit/merge/ResolveMerger.java

diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/merge/ResolveMerger.java b/org.eclipse.jgit/src/org/eclipse/jgit/merge/ResolveMerger.java
index 85b85cf..a6a287b 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/merge/ResolveMerger.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/merge/ResolveMerger.java
@@ -41,6 +41,7 @@
 import org.eclipse.jgit.annotations.Nullable;
 import org.eclipse.jgit.attributes.Attribute;
 import org.eclipse.jgit.attributes.Attributes;
+import org.eclipse.jgit.attributes.AttributesNodeProvider;
 import org.eclipse.jgit.diff.DiffAlgorithm;
 import org.eclipse.jgit.diff.DiffAlgorithm.SupportedAlgorithm;
 import org.eclipse.jgit.diff.RawText;
@@ -837,6 +838,13 @@ public enum MergeFailureReason {
 	@NonNull
 	private ContentMergeStrategy contentStrategy = ContentMergeStrategy.CONFLICT;
 
+	/**
+	 * The {@link AttributesNodeProvider} to use while merging trees.
+	 *
+	 * @since 6.10.1
+	 */
+	protected AttributesNodeProvider attributesNodeProvider;
+
 	private static MergeAlgorithm getMergeAlgorithm(Config config) {
 		SupportedAlgorithm diffAlg = config.getEnum(
 				CONFIG_DIFF_SECTION, null, CONFIG_KEY_ALGORITHM,
@@ -1836,6 +1844,18 @@ public void setWorkingTreeIterator(WorkingTreeIterator workingTreeIterator) {
 		this.workingTreeIterator = workingTreeIterator;
 	}
 
+	/**
+	 * Sets the {@link AttributesNodeProvider} to be used by this merger.
+	 *
+	 * @param attributesNodeProvider
+	 *            the attributeNodeProvider to set
+	 * @since 6.10.1
+	 */
+	public void setAttributesNodeProvider(
+			AttributesNodeProvider attributesNodeProvider) {
+		this.attributesNodeProvider = attributesNodeProvider;
+	}
+
 
 	/**
 	 * The resolve conflict way of three way merging
@@ -1880,6 +1900,9 @@ protected boolean mergeTrees(AbstractTreeIterator baseTree,
 					WorkTreeUpdater.createWorkTreeUpdater(db, dircache);
 			dircache = workTreeUpdater.getLockedDirCache();
 			tw = new NameConflictTreeWalk(db, reader);
+			if (attributesNodeProvider != null) {
+				tw.setAttributesNodeProvider(attributesNodeProvider);
+			}
 
 			tw.addTree(baseTree);
 			tw.setHead(tw.addTree(headTree));