Add stack trace printer support for structured logging

Introduce a new `StackTracePrinter` interface (and a standard
implementation) that can be used to print stack traces in a custom
form. The existing `StructuredLoggingJsonProperties` have been updated
with a nested `StackTrace` record that supports common customization
options or allows a custom `StackTracePrinter` to be used.

Closes gh-43864

Author: philwebb

spring-boot-project/spring-boot-docs/src/docs/antora/modules/reference/pages/features/logging.adoc

@@ -647,6 +647,57 @@ You can also declare implementations by listing them in a `META-INF/spring.facto
 
 
 
+[[features.logging.structured.customizing-stack-traces]]
+=== Customizing Structured Logging Stack Traces
+
+Complete stack traces are included in the JSON output whenever a message is logged with an exception.
+This amount of information may be costly to process by your log ingestion system, so you may want to tune the way that stack traces are printed.
+
+To do this, you can use one or more of the following properties:
+
+|===
+| Property | Description
+
+| configprop:logging.structured.json.stacktrace.root[]
+| Use `last` to print the root item last (same as Java) or `first` to print the root item first.
+
+| configprop:logging.structured.json.stacktrace.max-length[]
+| The maximum length that should be printed
+
+| configprop:logging.structured.json.stacktrace.max-throwable-depth[]
+| The maximum number of frames to print per stack trace (including common and suppressed frames)
+
+| configprop:logging.structured.json.stacktrace.include-common-frames[]
+| If common frames should be included or removed
+
+| configprop:logging.structured.json.stacktrace.include-hashes[]
+| If a hash of the stack trace should be included
+|===
+
+For example, the following will use root first stack traces, limit their length, and include hashes.
+
+[configprops,yaml]
+----
+logging:
+  structured:
+    json:
+      stacktrace:
+        root: first
+        max-length: 1024
+        include-common-frames: true
+        include-hashes: true
+----
+
+[TIP]
+====
+If you need complete control over stack trace printing you can set configprop:logging.structured.json.stacktrace.printer[] to the name of a javadoc:org.springframework.boot.logging.StackTracePrinter[] implementation.
+You can also set it to `logging-system` to force regular logging system stack trace output to be used.
+
+Your `StackTracePrinter` implementation can also include a constructor argument that accepts a javadoc:org.springframework.boot.logging.StandardStackTracePrinter[] if it wishes to apply further customization to the stack trace printer created from the properties.
+====
+
+
+
 [[features.logging.structured.other-formats]]
 === Supporting Other Structured Logging Formats
 

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/logging/StackTracePrinter.java

@@ -0,0 +1,57 @@
+/*
+ * Copyright 2012-2025 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.logging;
+
+import java.io.IOException;
+import java.io.UncheckedIOException;
+
+/**
+ * Interface that can be used to print the stack trace of a {@link Throwable}.
+ *
+ * @author Phillip Webb
+ * @since 3.5.0
+ * @see StandardStackTracePrinter
+ */
+@FunctionalInterface
+public interface StackTracePrinter {
+
+	/**
+	 * Return a {@link String} containing the printed stack trace for a given
+	 * {@link Throwable}.
+	 * @param throwable the throwable that should have its stack trace printed
+	 * @return the stack trace string
+	 */
+	default String printStackTraceToString(Throwable throwable) {
+		try {
+			StringBuilder out = new StringBuilder(4096);
+			printStackTrace(throwable, out);
+			return out.toString();
+		}
+		catch (IOException ex) {
+			throw new UncheckedIOException(ex);
+		}
+	}
+
+	/**
+	 * Prints a stack trace for the given {@link Throwable}.
+	 * @param throwable the throwable that should have its stack trace printed
+	 * @param out the destination to write output
+	 * @throws IOException on IO error
+	 */
+	void printStackTrace(Throwable throwable, Appendable out) throws IOException;
+
+}