WhiningBuilder

public final class Builder<MissingName extends Exception,MissingMIMEType extends Exception> {
  public Source build() throws MissingName, MissingMIMEType {
    if (this.name == null) {
      throw (MissingName)new Exception("name missing");
    }
    if (this.mimetype == null) {
      throw (MissingMIMEType)new Exception("MIME type missing");
    }
    // create and
    return source;
  }
 
 
  public static Builder<Exception,Exception> newFromText(String content) {
    // create new builder without name and MIME type
    return theBuilder;
  }
 
  public Builder<RuntimeException,MissingMIMEType> name(String name) {
    // specifying name
    this.name = name;
    // keeps the "mime type" exception unchanged but
    // turns the "name" exception into runtime one
    return (Builder<RuntimeException,MissingMIMEType>)this;
  }
 
  public Builder<MissingName,RuntimeException> mimeType(String mimeType) {
    // specifying MIME Type
    this.mimeType = mimeType;
    // keeps the "name" exception unchanged but
    // turns the "mime type" exception into runtime one
    return (Builder<MissingName,RuntimeException>)this;
  }
}
 
Please note that ''MissingName'' and ''MissingMIMEType'' are generics type parameters - e.g. they aren't real exceptions, just specifications/place holders for the actual {{JDK|java/lang|Exception}} subclass. This gives us early compile time warning as in [[ChameleonBuilder]]. When one tries to compile:
 
<source lang="java">
private static Source buildMySource() {
  return Source.newFromText("function hi() { print('Hi'; }").
    build();
}