diff --git a/README.md b/README.md
index 7846633..ff0fa73 100644
--- a/README.md
+++ b/README.md
@@ -7,7 +7,7 @@
 
 This library allows Java developers to consume Server Sent Events from a remote API, using [OkHttp](https://square.github.io/okhttp/) as the transport layer. The SSE spec is defined here: https://html.spec.whatwg.org/multipage/server-sent-events.html
 
-Starting in version 2.0, this library uses OkHttp 4.x and requires Java 8+. If you need support for OkHttp 3.x or Java 7, use the latest 1.x version.
+Starting in version 6.0, this library uses OkHttp 5.x and requires Java 8+ (or Android 5.0+). Versions 2.0 through 5.x use OkHttp 4.x. If you need support for OkHttp 3.x or Java 7, use the latest 1.x version.
 
 ## Contributing
 
diff --git a/build.gradle.kts b/build.gradle.kts
index 5de278a..42b255f 100644
--- a/build.gradle.kts
+++ b/build.gradle.kts
@@ -18,22 +18,23 @@ plugins {
     signing
     `maven-publish`
     idea
-    id("org.jetbrains.kotlin.jvm") version "1.6.10"
+    id("org.jetbrains.kotlin.jvm") version "2.1.21"
     id("io.github.gradle-nexus.publish-plugin") version "1.3.0" apply false
 }
 
 // Note about org.jetbrains.kotlin.jvm in the plugins block:
-// Normally we wouldn't have to explicitly list the Kotlin plugin here since we're
-// only building Java code. However-- possibly because OkHttp uses Kotlin-- if we
-// don't list the plugin here, then we're unable to use the "api" configuration in
-// dependencies even though that would normally be made available by the combination
-// of "java" and "java-library". See:
-// https://discuss.gradle.org/t/does-the-java-library-plugin-actually-do-anything-gradle-cant-do-natively/34361/5
-// We have to make sure the version shown here matches the version that is used by
-// OkHttp-- otherwise we will end up with an extra Kotlin runtime dependency in our
-// own pom.
-// This does not appear to be an issue with other Java projects such as
-// launchdarkly-java-sdk-common; there, we can just use "java" and "java-library".
+// This project is pure Java, but the Kotlin plugin must stay applied. With it applied,
+// maven-publish writes the resolved "okhttp-jvm" coordinates into our pom instead of
+// "okhttp". That matters because OkHttp 5.x publishes "okhttp" itself as an empty
+// Kotlin Multiplatform stub whose pom does not reference okhttp-jvm; only Gradle
+// consumers (via module metadata) can resolve it to the real JVM artifact. A pom of
+// ours pointing at "okhttp" would therefore give Maven-only consumers no OkHttp
+// classes at all. (Our Gradle module metadata still declares "okhttp", which Gradle
+// consumers resolve normally.)
+// Keep this plugin version matched to the Kotlin version OkHttp is built with (see
+// the kotlin-stdlib dependency in okhttp-jvm's pom for the OkHttp version above).
+// kotlin.stdlib.default.dependency=false in gradle.properties prevents the plugin
+// from adding kotlin-stdlib to our own pom.
 
 repositories {
     mavenLocal()
@@ -63,7 +64,7 @@ java {
 
 object Versions {
     const val launchdarklyLogging = "1.1.1"
-    const val okhttp = "4.12.0"
+    const val okhttp = "5.5.1"
 }
 
 dependencies {
diff --git a/gradle/wrapper/gradle-wrapper.jar b/gradle/wrapper/gradle-wrapper.jar
index 7454180..afba109 100644
Binary files a/gradle/wrapper/gradle-wrapper.jar and b/gradle/wrapper/gradle-wrapper.jar differ
diff --git a/gradle/wrapper/gradle-wrapper.properties b/gradle/wrapper/gradle-wrapper.properties
index 070cb70..b1624c4 100644
--- a/gradle/wrapper/gradle-wrapper.properties
+++ b/gradle/wrapper/gradle-wrapper.properties
@@ -1,5 +1,6 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-7.6-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-7.6.3-bin.zip
+networkTimeout=10000
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
diff --git a/gradlew b/gradlew
index 1b6c787..65dcd68 100755
--- a/gradlew
+++ b/gradlew
@@ -55,7 +55,7 @@
 #       Darwin, MinGW, and NonStop.
 #
 #   (3) This script is generated from the Groovy template
-#       https://github.com/gradle/gradle/blob/master/subprojects/plugins/src/main/resources/org/gradle/api/internal/plugins/unixStartScript.txt
+#       https://github.com/gradle/gradle/blob/HEAD/subprojects/plugins/src/main/resources/org/gradle/api/internal/plugins/unixStartScript.txt
 #       within the Gradle project.
 #
 #       You can find Gradle at https://github.com/gradle/gradle/.
@@ -80,10 +80,10 @@ do
     esac
 done
 
-APP_HOME=$( cd "${APP_HOME:-./}" && pwd -P ) || exit
-
-APP_NAME="Gradle"
+# This is normally unused
+# shellcheck disable=SC2034
 APP_BASE_NAME=${0##*/}
+APP_HOME=$( cd "${APP_HOME:-./}" && pwd -P ) || exit
 
 # Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
 DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
@@ -143,12 +143,16 @@ fi
 if ! "$cygwin" && ! "$darwin" && ! "$nonstop" ; then
     case $MAX_FD in #(
       max*)
+        # In POSIX sh, ulimit -H is undefined. That's why the result is checked to see if it worked.
+        # shellcheck disable=SC3045 
         MAX_FD=$( ulimit -H -n ) ||
             warn "Could not query maximum file descriptor limit"
     esac
     case $MAX_FD in  #(
       '' | soft) :;; #(
       *)
+        # In POSIX sh, ulimit -n is undefined. That's why the result is checked to see if it worked.
+        # shellcheck disable=SC3045 
         ulimit -n "$MAX_FD" ||
             warn "Could not set maximum file descriptor limit to $MAX_FD"
     esac
@@ -205,6 +209,12 @@ set -- \
         org.gradle.wrapper.GradleWrapperMain \
         "$@"
 
+# Stop when "xargs" is not available.
+if ! command -v xargs >/dev/null 2>&1
+then
+    die "xargs is not available"
+fi
+
 # Use "xargs" to parse quoted args.
 #
 # With -n1 it outputs one arg per line, with the quotes and backslashes removed.
diff --git a/gradlew.bat b/gradlew.bat
index ac1b06f..6689b85 100644
--- a/gradlew.bat
+++ b/gradlew.bat
@@ -14,7 +14,7 @@
 @rem limitations under the License.
 @rem
 
-@if "%DEBUG%" == "" @echo off
+@if "%DEBUG%"=="" @echo off
 @rem ##########################################################################
 @rem
 @rem  Gradle startup script for Windows
@@ -25,7 +25,8 @@
 if "%OS%"=="Windows_NT" setlocal
 
 set DIRNAME=%~dp0
-if "%DIRNAME%" == "" set DIRNAME=.
+if "%DIRNAME%"=="" set DIRNAME=.
+@rem This is normally unused
 set APP_BASE_NAME=%~n0
 set APP_HOME=%DIRNAME%
 
@@ -40,7 +41,7 @@ if defined JAVA_HOME goto findJavaFromJavaHome
 
 set JAVA_EXE=java.exe
 %JAVA_EXE% -version >NUL 2>&1
-if "%ERRORLEVEL%" == "0" goto execute
+if %ERRORLEVEL% equ 0 goto execute
 
 echo.
 echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
@@ -75,13 +76,15 @@ set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar
 
 :end
 @rem End local scope for the variables with windows NT shell
-if "%ERRORLEVEL%"=="0" goto mainEnd
+if %ERRORLEVEL% equ 0 goto mainEnd
 
 :fail
 rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of
 rem the _cmd.exe /c_ return code!
-if  not "" == "%GRADLE_EXIT_CONSOLE%" exit 1
-exit /b 1
+set EXIT_CODE=%ERRORLEVEL%
+if %EXIT_CODE% equ 0 set EXIT_CODE=1
+if not ""=="%GRADLE_EXIT_CONSOLE%" exit %EXIT_CODE%
+exit /b %EXIT_CODE%
 
 :mainEnd
 if "%OS%"=="Windows_NT" endlocal