Bug 553622 - Highlighting in context information no longer works

This change restores the previous behavior in case of a single
IContextInformationValidator, so it removes the regression.
The case of multiple validators will be treated in a separate change,
as it's not a regression but more a missing feature for mulitple completion
processors.

Change-Id: I9a826bc5ec43ea59c48d304b330d4a3ed2d7739b
Signed-off-by: Mickael Istria <mistria@redhat.com>
diff --git a/org.eclipse.jface.text/src/org/eclipse/jface/text/contentassist/CompositeContextInformationValidator.java b/org.eclipse.jface.text/src/org/eclipse/jface/text/contentassist/CompositeContextInformationValidator.java
index 1f2bd35..31ac39e 100644
--- a/org.eclipse.jface.text/src/org/eclipse/jface/text/contentassist/CompositeContextInformationValidator.java
+++ b/org.eclipse.jface.text/src/org/eclipse/jface/text/contentassist/CompositeContextInformationValidator.java
@@ -13,8 +13,9 @@
 import java.util.Arrays;
 
 import org.eclipse.jface.text.ITextViewer;
+import org.eclipse.jface.text.TextPresentation;
 
-class CompositeContextInformationValidator implements IContextInformationValidator {
+class CompositeContextInformationValidator implements IContextInformationValidator, IContextInformationPresenter {
 
 	private final IContextInformationValidator[] children;
 
@@ -32,4 +33,12 @@
 		return Arrays.stream(children).anyMatch(child -> child.isContextInformationValid(offset));
 	}
 
+	@Override
+	public boolean updatePresentation(int offset, TextPresentation presentation) {
+		if (children.length == 1 && children[0] instanceof IContextInformationPresenter) {
+			return ((IContextInformationPresenter) children[0]).updatePresentation(offset, presentation);
+		}
+		return false;
+	}
+
 }
diff --git a/org.eclipse.jface.text/src/org/eclipse/jface/text/contentassist/ContentAssistant.java b/org.eclipse.jface.text/src/org/eclipse/jface/text/contentassist/ContentAssistant.java
index 04c7e63..4da58e2 100644
--- a/org.eclipse.jface.text/src/org/eclipse/jface/text/contentassist/ContentAssistant.java
+++ b/org.eclipse.jface.text/src/org/eclipse/jface/text/contentassist/ContentAssistant.java
@@ -2120,6 +2120,8 @@
 				.toArray(IContextInformationValidator[]::new);
 		if (validators.length == 0) {
 			return null;
+		} else if (validators.length == 1) {
+			return validators[0];
 		}
 		return new CompositeContextInformationValidator(validators);
 	}
@@ -2146,6 +2148,8 @@
 				.toArray(IContextInformationValidator[]::new);
 		if (validators.length == 0) {
 			return null;
+		} else if (validators.length == 1) {
+			return validators[0];
 		}
 		return new CompositeContextInformationValidator(validators);
 	}