fix typo (#820)

src/main/java/org/assertj/core/error/ShouldBeEqual.java

@@ -92,7 +92,7 @@ public static AssertionErrorFactory shouldBeEqual(Object actual, Object expected
    * {@link #expected} description in case their string representation are the same (like 42 float and 42 double).
    * <p>
    * If JUnit 4 is in the classpath and the description is standard (no comparator was used and {@link #actual} and
-   * {@link #expected} string representation were differents), this method will instead create a
+   * {@link #expected} string representation were different), this method will instead create a
    * org.junit.ComparisonFailure that highlights the difference(s) between the expected and actual objects.
    * </p>
    * {@link AssertionError} stack trace won't show AssertJ related elements if {@link Failures} is configured to filter

src/test/java/org/assertj/core/api/filter/Filter_on_differents_properties_Test.java → src/test/java/org/assertj/core/api/filter/Filter_on_different_properties_Test.java

@@ -20,7 +20,7 @@
 import org.assertj.core.util.introspection.IntrospectionError;
 import org.junit.Test;
 
-public class Filter_on_differents_properties_Test extends AbstractTest_filter {
+public class Filter_on_different_properties_Test extends AbstractTest_filter {
 
   @Test
   public void should_filter_iterable_elements_on_different_properties() {