Cleanup code

Author: damianmalczewski

src/main/java/io/github/problem4j/core/DefaultProblem.java

@@ -16,9 +16,10 @@
 
 package io.github.problem4j.core;
 
+import static java.util.Collections.unmodifiableMap;
+
 import java.io.Serializable;
 import java.net.URI;
-import java.util.Collections;
 import java.util.HashMap;
 import java.util.Map;
 import org.jspecify.annotations.Nullable;
@@ -76,7 +77,7 @@ public int getStatus() {
 
   @Override
   public Map<String, Object> getExtensions() {
-    return Collections.unmodifiableMap(extensions);
+    return unmodifiableMap(extensions);
   }
 
   @Override
@@ -87,8 +88,7 @@ public boolean equals(@Nullable Object obj) {
     if (!(obj instanceof Problem)) {
       return false;
     }
-    Problem other = (Problem) obj;
-    return ProblemSupport.equals(this, other);
+    return ProblemSupport.equals(this, (Problem) obj);
   }
 
   @Override
@@ -129,8 +129,7 @@ public boolean equals(@Nullable Object obj) {
       if (!(obj instanceof Problem.Extension)) {
         return false;
       }
-      Problem.Extension other = (Problem.Extension) obj;
-      return ProblemSupport.equals(this, other);
+      return ProblemSupport.equals(this, (Problem.Extension) obj);
     }
 
     @Override

src/main/java/io/github/problem4j/core/DefaultProblemContext.java

@@ -16,8 +16,9 @@
 
 package io.github.problem4j.core;
 
+import static java.util.Collections.unmodifiableMap;
+
 import java.io.Serializable;
-import java.util.Collections;
 import java.util.HashMap;
 import java.util.Map;
 import org.jspecify.annotations.Nullable;
@@ -54,7 +55,7 @@ public ProblemContext put(String key, @Nullable String value) {
 
   @Override
   public Map<String, String> toMap() {
-    return Collections.unmodifiableMap(new HashMap<>(context));
+    return unmodifiableMap(new HashMap<>(context));
   }
 
   @Override
@@ -65,8 +66,7 @@ public boolean equals(@Nullable Object obj) {
     if (!(obj instanceof ProblemContext)) {
       return false;
     }
-    ProblemContext other = (ProblemContext) obj;
-    return ProblemSupport.equals(this, other);
+    return ProblemSupport.equals(this, (ProblemContext) obj);
   }
 
   @Override

src/main/java/io/github/problem4j/core/Problem.java

@@ -39,10 +39,6 @@
  *
  * In addition, custom extensions can be added to provide extra context.
  *
- * <p>Use {@link ProblemSupport#equals(Problem, Problem)}, {@link ProblemSupport#hashCode(Problem)},
- * and {@link ProblemSupport#toString(Problem)} as the canonical reference implementations of these
- * methods.
- *
  * @since 1.3.0
  */
 public interface Problem {
@@ -247,13 +243,6 @@ default ProblemBuilder toBuilder() {
   /**
    * Represents a single key-value extension in a {@link Problem}.
    *
-   * <p><b>Well-known contracts:</b>
-   *
-   * <p>Use {@link ProblemSupport#equals(Problem.Extension, Problem.Extension)}, {@link
-   * ProblemSupport#hashCode(Problem.Extension)}, and {@link
-   * ProblemSupport#toString(Problem.Extension)} as the canonical reference implementations of these
-   * methods.
-   *
    * @since 1.3.0
    */
   interface Extension {

src/main/java/io/github/problem4j/core/ProblemContext.java

@@ -23,12 +23,6 @@
  * Context passed for problem processing. Used by {@link ProblemMapper}. Provides access to values
  * used for message interpolation or metadata enrichment.
  *
- * <p><b>Well-known contracts:</b>
- *
- * <p>Use {@link ProblemSupport#equals(ProblemContext, ProblemContext)}, {@link
- * ProblemSupport#hashCode(ProblemContext)}, and {@link ProblemSupport#toString(ProblemContext)} as
- * the canonical reference implementations of these methods.
- *
  * @since 1.3.0
  */
 public interface ProblemContext {

src/test/java/io/github/problem4j/core/DefaultProblemBuilderTest.java

@@ -18,12 +18,12 @@
 
 import static io.github.problem4j.core.Problem.extension;
 import static java.util.Collections.emptyMap;
+import static java.util.Collections.singletonList;
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatThrownBy;
 
 import java.net.URI;
 import java.util.Arrays;
-import java.util.Collections;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.Optional;
@@ -249,7 +249,7 @@ void givenExtensionSetThenUnsetViaCollection_shouldRemoveExtension() {
     Problem problem =
         newInstance()
             .extension("name", "Mark")
-            .extensions(Collections.singletonList(Problem.extension("name", null)))
+            .extensions(singletonList(Problem.extension("name", null)))
             .build();
 
     assertThat(problem.getExtensions()).isEmpty();