public Builder addEntry(
        Path sourceFile, AbsoluteUnixPath pathInContainer, FilePermissions permissions) {
      layerBuilder.addEntry(sourceFile, pathInContainer, permissions);
      return this;
    }
Adds an entry to the layer with the given permissions. Only adds the single source file to
the exact path in the container file system. See {@link Builder#addEntry(Path,
AbsoluteUnixPath)} for more information.

@param sourceFile the source file to add to the layer
@param pathInContainer the path in the container file system corresponding to the {@code
    sourceFile}
@param permissions the file permissions on the container
@return this
@see Builder#addEntry(Path, AbsoluteUnixPath)
@see FilePermissions#DEFAULT_FILE_PERMISSIONS
@see FilePermissions#DEFAULT_FOLDER_PERMISSIONS
jib-core/src/main/java/com/google/cloud/tools/jib/api/LayerConfiguration.java