Remove the dependency on Google Guava

[leakingtapan]

in favor of Java 8 lambda

[overholts]

Just took a look at this. We're using the following pieces of functionality:

• Guava functional interfaces (can be replaced with java.util.function.* interfaces)
• Preconditions#checkNotNull (can be replaced with Objects#requireNonNull)
• Collection Utilities are used to instantiate various collections implementations (can just initialize directly)
• Immutable Collections are used in the following places
  • default supplier config
  • supplier-driven basic object factory
  • orchestrating (default) object factory
  • collections factory methods

There isn't a language-provided drop in replacement for Guava's immutable collections. Java's native "unmodifiable collections" have some disadvantages.

That being said, we aren't really leveraging any non-trivial Guava functionality besides returning Immutable collections. Do you think it makes sense to keep it or drop it?

(Also if we keep it, worth adding a note to the documentation that it should be fine to override at runtime with more or less any version of Guava - I've been asked about that)

[leakingtapan]

How is overriding with any version of Guava possible?