public SmithyBuild registerSources(Path... pathToSources) {
        for (Path path : pathToSources) {
            addSource(path);
        }
        return this;
    }
Registers the given paths as sources of the model being built.

<p>There are typically two kinds of models that are added to a build:
source models and discovered models. Discovered models are someone
else's models. Source models are the models owned by the package
being built.

<p>Source models are copied into the automatically executed "manifest"
plugin. If no transformations were applied to the sources, then the
source models are copied literally into the manifest directory output.
Otherwise, a modified version of the source models are copied.

<p>When a directory is provided, all of the files in the directory are
treated as sources, and they are relativized to remove the directory.
When a file is provided, the directory that contains that file is used
as a source. All of the relativized files resolved in sources must be
unique across the entire set of files. The sources directories are
essentially flattened into a single directory.

<p>Unsupported model files are ignored and not treated as sources.
This can happen when adding model files from a directory that contains
a mix of model files and non-model files. Filtering models here prevents
unsupported files from appearing in places like JAR manifest files where
they are not allowed.

@param pathToSources Path to source directories to mark.
@return Returns the builder.
smithy-build/src/main/java/software/amazon/smithy/build/SmithyBuild.java