code: public void setInitializer(/* @Nullable */ JvmField field, /* @Nullable */ XExpression expr) {
  		if (field == null || expr == null)
  			return;
  		removeExistingBody(field);
  		associator.associateLogicalContainer(expr, field);
  	}
docs: Sets the given {@link JvmField} as the logical container for the given {@link XExpression}.
  This defines the context and the scope for the given expression.
  
  @param field
  the {@link JvmField} that is initialized by the expression. If <code>null</code> this method does nothing.
  @param expr
  the initialization expression. Can be <code>null</code> in which case this function does nothing.