diff --git a/org.eclipse.jdt.core/model/org/eclipse/jdt/core/IClasspathAttribute.java b/org.eclipse.jdt.core/model/org/eclipse/jdt/core/IClasspathAttribute.java
index 1c66864..20e7152 100644
--- a/org.eclipse.jdt.core/model/org/eclipse/jdt/core/IClasspathAttribute.java
+++ b/org.eclipse.jdt.core/model/org/eclipse/jdt/core/IClasspathAttribute.java
@@ -77,10 +77,11 @@
 	 * <ul> 
 	 * <li>	Encoding explicitly set on the source file (java or zip), i.e. <code>org.eclipse.core.resources.IFile#getCharset(false)</code> </li>
 	 * <li>	Encoding set on the corresponding classpath entry </li>
-	 * <li> If the source attachment is a member of the project, then the project's default charSet</li>
-	 * <li> Workspace default charSet </li>
+	 * <li> If the source attachment is a folder, then the encoding determined by the file content if detectable </li>
+	 * <li> If the source attachment is in the workspace, then the encoding of the enclosing resources</li>
 	 * </ul>
 	 * 
+	 * @see org.eclipse.core.resources.IFile#getCharset()
 	 * @since 3.8
 	 */
 	String SOURCE_ATTACHMENT_ENCODING = "source_encoding"; //$NON-NLS-1$
diff --git a/org.eclipse.jdt.core/model/org/eclipse/jdt/internal/core/SourceMapper.java b/org.eclipse.jdt.core/model/org/eclipse/jdt/internal/core/SourceMapper.java
index c1c3e86..8c14620 100644
--- a/org.eclipse.jdt.core/model/org/eclipse/jdt/internal/core/SourceMapper.java
+++ b/org.eclipse.jdt.core/model/org/eclipse/jdt/internal/core/SourceMapper.java
@@ -246,11 +246,11 @@
 	int anonymousCounter;
 	int anonymousClassName;
 
+	String encoding;
+	String defaultEncoding;
 	/**
 	 *Options to be used
 	 */
-	String encoding;
-	String defaultEncoding;
 	Map options;
 
 	/**
@@ -1027,6 +1027,7 @@
 				try {
 					// Order of preference: charSet supplied, this.encoding or this.defaultEncoding in that order
 					try {
+						// Use the implicit encoding only when the source attachment's encoding hasn't been explicitly set.
 						charSet = ((IFile) res).getCharset(this.encoding == null);
 					} catch (CoreException e) {
 						// Ignore