diff --git a/.github/workflows/dart_ci.yaml b/.github/workflows/dart_ci.yaml
new file mode 100644
index 0000000..6e7437f
--- /dev/null
+++ b/.github/workflows/dart_ci.yaml
@@ -0,0 +1,31 @@
+name: Dart CI
+
+on:
+  push:
+    branches:
+      - 'master'
+      - 'test_consume_*'
+  pull_request:
+    branches:
+      - '*'
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        sdk: [ stable, beta, dev ]
+    steps:
+      - uses: actions/checkout@v2
+      - uses: dart-lang/setup-dart@v1
+        with:
+          sdk: ${{ matrix.sdk }}
+      - name: Install dependencies
+        run: dart pub get
+      - name: Check formatting
+        run: dart format --output=none --set-exit-if-changed .
+        if: ${{ matrix.sdk == 'stable' }}
+      - name: Analyze project source
+        run: dart analyze
+      - name: Run tests
+        run: dart test
diff --git a/.travis.yml b/.travis.yml
deleted file mode 100644
index 5eb5e1c..0000000
--- a/.travis.yml
+++ /dev/null
@@ -1,26 +0,0 @@
-language: dart
-
-# Re-use downloaded pub packages everywhere.
-cache:
-  directories:
-    - $HOME/.pub-cache
-
-jobs:
-  include:
-    - dart: 2.3.0
-      name: "SDK: 2.3.0"
-      script:
-        - dartanalyzer .
-        - pub run test
-    - dart: stable
-      name: "SDK: stable"
-      script:
-        - dartanalyzer .
-        - dartfmt -n --set-exit-if-changed .
-        - pub run dependency_validator
-        - pub run test
-    - dart: dev
-      name: "SDK: dev"
-      script:
-        - dartanalyzer .
-        - pub run test
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7c97ac1..888aecb 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,9 @@
 # Changelog
 
+## 2.0.0
+
+- Stable null safe release.
+
 ## 1.3.0
 
 - Add a `removeQueryParam()` method.
diff --git a/Dockerfile b/Dockerfile
index b915d84..de35360 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,5 +1,5 @@
 FROM google/dart:2
 WORKDIR /build/
 ADD pubspec.yaml .
-RUN pub get
+RUN dart pub get
 FROM scratch
diff --git a/analysis_options.yaml b/analysis_options.yaml
index eca95d4..f09d80b 100644
--- a/analysis_options.yaml
+++ b/analysis_options.yaml
@@ -1,572 +1 @@
-# analysis_options.yaml docs: https://www.dartlang.org/guides/language/analysis-options 
-analyzer:
-  # Strong mode is required. Applies to the current project.
-  strong-mode:
-    # When compiling to JS, both implicit options apply to the current 
-    # project and all dependencies. They are useful to find possible 
-    # Type fixes or areas for explicit typing.
-    implicit-casts: true
-    implicit-dynamic: true
-
-# ALL lint rules are included. Unused lints should be commented
-# out with a reason. An up to date list of all options is here
-# http://dart-lang.github.io/linter/lints/options/options.html
-# Descriptions of each rule is here http://dart-lang.github.io/linter/lints/
-#
-# To ignore a lint rule on a case by case basic in code just add a comment
-# above it or at the end of the line like: // ignore: <linter rule>
-# example: // ignore: invalid_assignment, const_initialized_with_non_constant_value
-#
-# More info about configuring analysis_options.yaml files
-# https://www.dartlang.org/guides/language/analysis-options#excluding-lines-within-a-file
-linter:
-  rules:
-    # Declare method return types.
-    # recommendation: recommended
-    # reason: React component render() method can return either ReactElement or false
-    # 0 issues
-    - always_declare_return_types
-
-    # Separate the control structure expression from its statement.
-    # recommendation: optional
-    # 0 issues
-    - always_put_control_body_on_new_line
-
-    # Put @required named parameters first.
-    # recommendation: recommended
-    # 0 issues
-    - always_put_required_named_parameters_first
-
-    # Use @required.
-    # recommendation: recommended
-    # 0 issues
-    - always_require_non_null_named_parameters
-
-    # Specify type annotations.
-    # recommendation: recommended
-    # FIXME: 55 lint(s)
-    # - always_specify_types
-
-    # Annotate overridden members.
-    # recommendation: required
-    # 0 issues
-    - annotate_overrides
-
-    # Avoid annotating with dynamic when not required.
-    # recommendation: optional
-    # FIXME: 1 lint(s)
-    # - avoid_annotating_with_dynamic
-
-    # Avoid using `as`.
-    # recommendation: optional
-    # 0 issues
-    - avoid_as
-
-    # Avoid bool literals in conditional expressions.
-    # recommendation: optional
-    # 0 issues
-    - avoid_bool_literals_in_conditional_expressions
-
-    # Avoid catches without on clauses.
-    # recommendation: optional
-    # 0 issues
-    - avoid_catches_without_on_clauses
-
-    # Don't explicitly catch Error or types that implement it.
-    # recommendation: optional
-    # 0 issues
-    - avoid_catching_errors
-
-    # Avoid defining a class that contains only static members.
-    # recommendation: recommended
-    # 0 issues
-    - avoid_classes_with_only_static_members
-
-    # Avoid empty else statements.
-    # recommendation: required
-    # 0 issues
-    - avoid_empty_else
-
-    # Avoid using `forEach` with a function literal.
-    # recommendation: recommended
-    # reason: Use for (x in y) or forEach(someFunc) instead
-    # 0 issues
-    - avoid_function_literals_in_foreach_calls
-
-    # Don't explicitly initialize variables to null.
-    # recommendation: recommended
-    # 0 issues
-    - avoid_init_to_null
-
-    # Don't check for null in custom == operators.
-    # recommendation: recommended
-    # 0 issues
-    - avoid_null_checks_in_equality_operators
-
-    # Avoid positional boolean parameters.
-    # recommendation: recommended
-    # 0 issues
-    - avoid_positional_boolean_parameters
-
-    # Avoid private typedef functions.
-    # recommendation: optional
-    # 0 issues
-    - avoid_private_typedef_functions
-
-    # Avoid relative imports for files in `lib/`.
-    # recommendation: recommended
-    # reason: JS compilation will be faster without relative imports. Use package imports.
-    # 0 issues
-    - avoid_relative_lib_imports
-
-    # Don't rename parameters of overridden methods.
-    # recommendation: optional
-    # 0 issues
-    - avoid_renaming_method_parameters
-
-    # Avoid return types on setters.
-    # recommendation: required
-    # 0 issues
-    - avoid_return_types_on_setters
-
-    # Avoid returning null from members whose return type is bool, double, int, or num.
-    # recommendation: optional
-    # 0 issues
-    - avoid_returning_null
-
-    # Avoid returning this from methods just to enable a fluent interface.
-    # recommendation: recommended
-    # 0 issues
-    - avoid_returning_this
-
-    # Avoid setters without getters.
-    # recommendation: recommended
-    # 0 issues
-    - avoid_setters_without_getters
-
-    # Avoid single cascade in expression statements.
-    # recommendation: optional
-    # 0 issues
-    - avoid_single_cascade_in_expression_statements
-
-    # Avoid slow async `dart:io` methods.
-    # recommendation: recommended
-    # 0 issues
-    - avoid_slow_async_io
-
-    # Avoid types as parameter names.
-    # recommendation: optional
-    # 0 issues
-    - avoid_types_as_parameter_names
-
-    # Avoid annotating types for function expression parameters.
-    # recommendation: optional
-    # 0 issues
-    - avoid_types_on_closure_parameters
-
-    # Avoid defining unused paramters in constructors.
-    # recommendation: recommended
-    # 0 issues
-    - avoid_unused_constructor_parameters
-
-    # Await only futures.
-    # recommendation: required
-    # 0 issues
-    - await_only_futures
-
-    # Name types using UpperCamelCase.
-    # recommendation: optional
-    # 0 issues
-    - camel_case_types
-
-    # Cancel instances of dart.async.StreamSubscription.
-    # recommendation: required
-    # 0 issues
-    - cancel_subscriptions
-
-    # Cascade consecutive method invocations on the same reference.
-    # recommendation: optional
-    # 0 issues
-    - cascade_invocations
-
-    # Close instances of `dart.core.Sink`.
-    # recommendation: required
-    # 0 issues
-    - close_sinks
-
-    # Only reference in scope identifiers in doc comments.
-    # recommendation: optional
-    # 0 issues
-    - comment_references
-
-    # Prefer using lowerCamelCase for constant names.
-    # recommendation: optional
-    # 0 issues
-    - constant_identifier_names
-
-    # Avoid control flow in finally blocks.
-    # recommendation: required
-    # 0 issues
-    - control_flow_in_finally
-
-    # Adhere to Effective Dart Guide directives sorting conventions.
-    # recommendation: required
-    # 0 issues
-    - directives_ordering
-
-    # Avoid empty catch blocks.
-    # recommendation: recommended
-    # 0 issues
-    - empty_catches
-
-    # Use `;` instead of `{}` for empty constructor bodies.
-    # recommendation: recommended
-    # 0 issues
-    - empty_constructor_bodies
-
-    # Avoid empty statements.
-    # recommendation: required
-    # 0 issues
-    - empty_statements
-
-    # Always override `hashCode` if overriding `==`.
-    # recommendation: required
-    # 0 issues
-    - hash_and_equals
-
-    # Don't import implementation files from another package.
-    # recommendation: required
-    # 0 issues
-    - implementation_imports
-
-    # Conditions should not unconditionally evaluate to `true` or to `false`.
-    # recommendation: required
-    # 0 issues
-    - invariant_booleans
-
-    # Invocation of Iterable<E>.contains with references of unrelated types.
-    # recommendation: required
-    # 0 issues
-    - iterable_contains_unrelated_type
-
-    # Join return statement with assignment when possible.
-    # recommendation: optional
-    # 0 issues
-    - join_return_with_assignment
-
-    # Name libraries and source files using `lowercase_with_underscores`.
-    # recommendation: recommended
-    # 0 issues
-    - library_names
-
-    # Use `lowercase_with_underscores` when specifying a library prefix.
-    # recommendation: recommended
-    # 0 issues
-    - library_prefixes
-
-    # Invocation of `remove` with references of unrelated types.
-    # recommendation: required
-    # 0 issues
-    - list_remove_unrelated_type
-
-    # Boolean expression composed only with literals.
-    # recommendation: required
-    # 0 issues
-    - literal_only_boolean_expressions
-
-    # Don't use adjacent strings in list.
-    # recommendation: required
-    # 0 issues
-    - no_adjacent_strings_in_list
-
-    # Don't use more than one case with same value.
-    # recommendation: required
-    # 0 issues
-    - no_duplicate_case_values
-
-    # Name non-constant identifiers using lowerCamelCase.
-    # recommendation: recommended
-    # 0 issues
-    - non_constant_identifier_names
-
-    # Omit type annotations for local variables.
-    # recommendation: avoid
-    # reason: Conflicts with always_specify_types. Recommend commenting this one out.
-    # 0 issues
-    # - omit_local_variable_types
-
-    # Avoid defining a one-member abstract class when a simple function will do.
-    # recommendation: optional
-    # 0 issues
-    - one_member_abstracts
-
-    # Only throw instances of classes extending either Exception or Error.
-    # recommendation: required
-    # 0 issues
-    - only_throw_errors
-
-    # Don't override fields.
-    # recommendation: optional
-    # 0 issues
-    - overridden_fields
-
-    # Provide doc comments for all public APIs.
-    # recommendation: optional
-    # 0 issues
-    - package_api_docs
-
-    # Use `lowercase_with_underscores` for package names.
-    # recommendation: recommended
-    # 0 issues
-    - package_names
-
-    # Prefix library names with the package name and a dot-separated path.
-    # recommendation: recommended
-    # 0 issues
-    - package_prefixed_library_names
-
-    # Don't reassign references to parameters of functions or methods.
-    # recommendation: optional
-    # 0 issues
-    - parameter_assignments
-
-    # Use adjacent strings to concatenate string literals.
-    # recommendation: optional
-    # 0 issues
-    - prefer_adjacent_string_concatenation
-
-    # Prefer putting asserts in initializer list.
-    # recommendation: optional
-    # 0 issues
-    - prefer_asserts_in_initializer_lists
-
-    # Use collection literals when possible.
-    # recommendation: optional
-    # 0 issues
-    - prefer_collection_literals
-
-    # Prefer using `??=` over testing for null.
-    # recommendation: optional
-    # 0 issues
-    - prefer_conditional_assignment
-
-    # Prefer const with constant constructors.
-    # recommendation: optional
-    # 0 issues
-    - prefer_const_constructors
-
-    # Prefer declare const constructors on `@immutable` classes.
-    # recommendation: optional
-    # 0 issues
-    - prefer_const_constructors_in_immutables
-
-    # Prefer const over final for declarations.
-    # recommendation: recommended
-    # 0 issues
-    - prefer_const_declarations
-
-    # Prefer const literals as parameters of constructors on @immutable classes.
-    # recommendation: optional
-    # 0 issues
-    - prefer_const_literals_to_create_immutables
-
-    # Prefer defining constructors instead of static methods to create instances.
-    # recommendation: optional
-    # 0 issues
-    - prefer_constructors_over_static_methods
-
-    # Use contains for `List` and `String` instances.
-    # recommendation: optional
-    # 0 issues
-    - prefer_contains
-
-    # Prefer equal for default values.
-    # recommendation: optional
-    # FIXME: 1 lint(s)
-    # - prefer_equal_for_default_values
-
-    # Use => for short members whose body is a single return statement.
-    # recommendation: optional
-    # 0 issues
-    - prefer_expression_function_bodies
-
-    # Private field could be final.
-    # recommendation: optional
-    # 0 issues
-    - prefer_final_fields
-
-    # Prefer final for variable declaration if reference is not reassigned.
-    # recommendation: optional
-    # reason: Generates a lot of lint since people use var a lot for local variables.
-    # 0 issues
-    - prefer_final_locals
-
-    # Use `forEach` to only apply a function to all the elements.
-    # recommendation: optional
-    # 0 issues
-    - prefer_foreach
-
-    # Use a function declaration to bind a function to a name.
-    # recommendation: optional
-    # 0 issues
-    - prefer_function_declarations_over_variables
-
-    # Use initializing formals when possible.
-    # recommendation: recommended
-    # 0 issues
-    - prefer_initializing_formals
-
-    # Use interpolation to compose strings and values.
-    # recommendation: optional
-    # 0 issues
-    - prefer_interpolation_to_compose_strings
-
-    # Use `isEmpty` for Iterables and Maps.
-    # recommendation: optional
-    # 0 issues
-    - prefer_is_empty
-
-    # Use `isNotEmpty` for Iterables and Maps.
-    # recommendation: optional
-    # 0 issues
-    - prefer_is_not_empty
-
-    # Prefer single quotes where they won't require escape sequences.
-    # recommendation: optional
-    # 0 issues
-    - prefer_single_quotes
-
-    # Prefer typing uninitialized variables and fields.
-    # recommendation: optional
-    # 0 issues
-    - prefer_typing_uninitialized_variables
-
-    # Document all public members.
-    # recommendation: optional
-    # reason: Can get annoying for React component lifecycle methods, constructors.
-    # 0 issues
-    - public_member_api_docs
-
-    # Property getter recursively returns itself.
-    # recommendation: optional
-    # 0 issues
-    - recursive_getters
-
-    # Prefer using /// for doc comments.
-    # recommendation: recommended
-    # 0 issues
-    - slash_for_doc_comments
-
-    # Sort constructor declarations before method declarations.
-    # recommendation: optional
-    # 0 issues
-    - sort_constructors_first
-
-    # Sort unnamed constructor declarations first.
-    # recommendation: optional
-    # 0 issues
-    - sort_unnamed_constructors_first
-
-    # Test type arguments in operator ==(Object other).
-    # recommendation: required
-    # 0 issues
-    - test_types_in_equals
-
-    # Avoid `throw` in finally block.
-    # recommendation: required
-    # 0 issues
-    - throw_in_finally
-
-    # Type annotate public APIs.
-    # recommendation: recommended
-    # reason: React component render() method can return either ReactElement or false. Use overrides.
-    # 0 issues
-    - type_annotate_public_apis
-
-    # Don't type annotate initializing formals.
-    # recommendation: optional
-    # 0 issues
-    - type_init_formals
-
-    # Await future-returning functions inside async function bodies.
-    # recommendation: recommended
-    # 0 issues
-    - unawaited_futures
-
-    # Avoid using braces in interpolation when not needed.
-    # recommendation: optional
-    # 0 issues
-    - unnecessary_brace_in_string_interps
-
-    # Avoid wrapping fields in getters and setters just to be "safe".
-    # recommendation: optional
-    # 0 issues
-    - unnecessary_getters_setters
-
-    # Don't create a lambda when a tear-off will do.
-    # recommendation: optional
-    # 0 issues
-    - unnecessary_lambdas
-
-    # Avoid null in null-aware assignment.
-    # recommendation: optional
-    # 0 issues
-    - unnecessary_null_aware_assignments
-
-    # Avoid using `null` in `if null` operators.
-    # recommendation: optional
-    # 0 issues
-    - unnecessary_null_in_if_null_operators
-
-    # Don't override a method to do a super method invocation with the same parameters.
-    # recommendation: optional
-    # 0 issues
-    - unnecessary_overrides
-
-    # Unnecessary parenthesis can be removed.
-    # recommendation: optional
-    # 0 issues
-    - unnecessary_parenthesis
-
-    # Avoid using unnecessary statements.
-    # recommendation: required
-    # 0 issues
-    - unnecessary_statements
-
-    # Don't access members with `this` unless avoiding shadowing.
-    # recommendation: recommended
-    # 0 issues
-    - unnecessary_this
-
-    # Equality operator `==` invocation with references of unrelated types.
-    # recommendation: required
-    # reason: Comparing references of a type where neither is a subtype of the other most likely will return false and might not reflect programmer's intent.
-    # 0 issues
-    - unrelated_type_equality_checks
-
-    # Use rethrow to rethrow a caught exception.
-    # recommendation: optional
-    # 0 issues
-    - use_rethrow_when_possible
-
-    # Use a setter for operations that conceptually change a property.
-    # recommendation: optional
-    # 0 issues
-    - use_setters_to_change_properties
-
-    # Use string buffer to compose strings.
-    # recommendation: optional
-    # 0 issues
-    - use_string_buffers
-
-    # Start the name of the method with to/_to or as/_as if applicable.
-    # recommendation: optional
-    # 0 issues
-    - use_to_and_as_if_applicable
-
-    # Use valid regular expression syntax.
-    # recommendation: required
-    # 0 issues
-    - valid_regexps
-
-
+include: package:workiva_analysis_options/v1.yaml
diff --git a/lib/fluri.dart b/lib/fluri.dart
index 0565f30..72f380c 100644
--- a/lib/fluri.dart
+++ b/lib/fluri.dart
@@ -96,8 +96,8 @@ class Fluri extends FluriMixin {
   /// Construct a new [Fluri] instance.
   ///
   /// A starting [uri] may be supplied which will be parsed by [Uri.parse].
-  Fluri([String uri]) {
-    this.uri = Uri.parse(uri != null ? uri : '');
+  Fluri([String? uri]) {
+    this.uri = Uri.parse(uri ?? '');
   }
 
   /// Construct a new [Fluri] instance from another [Fluri] instance.
@@ -142,7 +142,7 @@ class FluriMixin {
 
   /// The full URI.
   Uri get uri => _uri;
-  set uri(Uri uri) {
+  set uri(Uri? uri) {
     _uri = uri ?? Uri.parse('');
   }
 
@@ -234,7 +234,7 @@ class FluriMixin {
   void removeQueryParam(String param) {
     _uri = _uri.replace(queryParameters: {
       for (final key in queryParametersAll.keys)
-        if (key != param) key: List.of(queryParametersAll[key]),
+        if (key != param) key: List.of(queryParametersAll[key]!),
     });
   }
 
@@ -253,11 +253,11 @@ class FluriMixin {
   void updateQuery(
       Map<String, dynamic /*String|Iterable<String>*/ > queryParametersToUpdate,
       {bool mergeValues = false}) {
-    final newQueryParameters = <String, List<String>>{};
+    final newQueryParameters = <String, Set<String>>{};
 
     // Copy the current query param values.
     queryParametersAll.forEach((key, value) {
-      newQueryParameters[key] = List.from(value);
+      newQueryParameters[key] = value.toSet();
     });
 
     // Update the query using the given params.
@@ -265,19 +265,15 @@ class FluriMixin {
       // Initialize or reset the value list if it either does not already exist,
       // or if we're not merging values.
       if (!mergeValues || !newQueryParameters.containsKey(key)) {
-        newQueryParameters[key] = [];
+        newQueryParameters[key] = <String>{};
       }
 
       // Add the param value(s) while eliminating duplicates.
       // Throw an ArgumentError if any value is invalid.
-      if (value is String && !newQueryParameters.containsValue(value)) {
-        newQueryParameters[key].add(value);
+      if (value is String) {
+        newQueryParameters[key]!.add(value);
       } else if (value is Iterable<String>) {
-        for (var v in value) {
-          if (!newQueryParameters[key].contains(v)) {
-            newQueryParameters[key].add(v);
-          }
-        }
+        newQueryParameters[key]!.addAll(value);
       } else {
         throw ArgumentError('Query parameter "$key" has value "$value" '
             'which is not a String or an Iterable<String>.');
diff --git a/pubspec.yaml b/pubspec.yaml
index fe3ce47..b98add8 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,9 +1,9 @@
 name: fluri
-version: 1.3.0
+version: 2.0.0
 description: Fluri is a fluent URI library built to make URI mutation easy.
 homepage: https://github.com/Workiva/fluri
 environment:
-  sdk: ">=2.3.0 <3.0.0"
+  sdk: '>=2.12.0 <3.0.0'
 dev_dependencies:
-  dependency_validator: ^1.4.0
-  test: ^1.9.2
+  test: ^1.16.5
+  workiva_analysis_options: ^1.1.0
diff --git a/test/fluri_test.dart b/test/fluri_test.dart
index ca54ae1..ee705aa 100644
--- a/test/fluri_test.dart
+++ b/test/fluri_test.dart
@@ -202,6 +202,26 @@ void commonFluriTests(FluriMixin getFluri()) {
           unorderedEquals(['binary', 'json', 'text']));
     });
 
+    test('should eliminate duplicate values when updating query parameters',
+        () {
+      expect(
+          (getFluri()
+                ..updateQuery({
+                  'dedupe': ['foo', 'bar']
+                })
+                ..updateQuery({
+                  'dedupe': ['foo', 'baz']
+                }, mergeValues: true))
+              .queryParametersAll,
+          containsPair('dedupe', ['foo', 'bar', 'baz']));
+      expect(
+          (getFluri()
+                ..updateQuery({'dedupe': 'foobaz'})
+                ..updateQuery({'dedupe': 'foobaz'}, mergeValues: true))
+              .queryParametersAll,
+          containsPair('dedupe', ['foobaz']));
+    });
+
     test(
         'should throw if invalid param value is given when setting a single query parameter',
         () {
@@ -241,7 +261,7 @@ void main() {
   const url = 'http://example.com/path/to/resource?limit=10&format=list#test';
 
   group('Fluri', () {
-    Fluri fluri;
+    late Fluri fluri;
 
     setUp(() {
       fluri = Fluri(url);
@@ -294,8 +314,8 @@ void main() {
   });
 
   group('FluriMixin', () {
-    ExtendingClass extender;
-    MixingClass mixer;
+    late ExtendingClass extender;
+    late MixingClass mixer;
 
     setUp(() {
       extender = ExtendingClass(url);