Extract dedicated interfaces instead of generic JDK types

[Legioth]

Related to #22843

[github-actions]

Format Checker Report

There are 19 files with format errors

• To see a complete report of formatting issues, download the differences artifact

• To fix the build, please run mvn spotless:apply in your branch and commit the changes.

• Optionally you might add the following line in your .git/hooks/pre-commit file:

  mvn spotless:apply
  

Here is the list of files with format issues in your PR:

signals/src/main/java/com/vaadin/signals/AbstractSignal.java
signals/src/main/java/com/vaadin/signals/ListSignal.java
signals/src/main/java/com/vaadin/signals/MapSignal.java
signals/src/main/java/com/vaadin/signals/NodeSignal.java
signals/src/main/java/com/vaadin/signals/NumberSignal.java
signals/src/main/java/com/vaadin/signals/ReferenceSignal.java
signals/src/main/java/com/vaadin/signals/Signal.java
signals/src/main/java/com/vaadin/signals/ValueSignal.java
signals/src/main/java/com/vaadin/signals/function/CommandValidator.java
signals/src/main/java/com/vaadin/signals/function/ValueSupplier.java
signals/src/main/java/com/vaadin/signals/impl/CommandsAndHandlers.java
signals/src/main/java/com/vaadin/signals/impl/ComputedSignal.java
signals/src/main/java/com/vaadin/signals/impl/Effect.java
signals/src/main/java/com/vaadin/signals/impl/MutableTreeRevision.java
signals/src/main/java/com/vaadin/signals/impl/SignalTree.java
signals/src/main/java/com/vaadin/signals/impl/StagedTransaction.java
signals/src/main/java/com/vaadin/signals/impl/Transaction.java
signals/src/test/java/com/vaadin/signals/impl/EffectTest.java
signals/src/test/java/com/vaadin/signals/impl/StagedTransactionTest.java