Message view with just a return value generates empty body

[Céline Bensoussan]

When the message view defined for an operation only contains a return value as shown in the figure, the code generator assumes empty message view and returns null inside the body of the operation:

ArrayList<X> getMyXs() {
  /* TODO: No message view defined */
  return null;
}

[Matthias Schoettle]

References #405: Removes specific selection from message fragments.

When retrieving messages for an operation (i.e., the message defining an operation), the query also considers nested definitions. When checking whether an operation is actually defined, the send event of the reply message is filtered out. However, in case there's just a reply with a value, this leads to no message fragments, i.e., no behaviour is found.

This selection is removed, because it is not required in that case.

→ <<cset 41e964a2e594>>

[Matthias Schoettle]

Merged in Issues/fixes-mv-codegen (pull request #83).