You can set the following properties for the Import Management Tool:
If set to Search in Well-Known Packages, the packages in the List of Well-Known Packages property are searched for unresolved identifiers. If unresolved identifiers are found, a package is suggested in Step 1 of the Import Management Tool. You can override all Import Management Tool suggested actions.
If a source file contains more single-name import statements from a package than the value of this property, the Import Management Tool changes the single-name imports into a package import. Similarly, if a source file contains fewer classes than this threshold from a single package, the package import statement is changed to single-name import statements.