Add new merge strategy Fail to PropertiesFileTransformer

[snazy]

Refs #1848.

---

• CHANGELOG's "Unreleased" section has been updated, if applicable.

[snazy]

Wait a sec before merging this...
I think the Gradle configuration cache "does not like" lazy's... (looking)

[snazy]

Wait a sec before merging this... I think the Gradle configuration cache "does not like" lazy's... (looking)

Ah, strike that

[snazy]

All good here

[Goooler]

Suggested change

	assertThat(result.output).contains(
	// TODO EXPERIMENT
	"""
	Execution failed for task ':shadowJar'.
	> The following properties files have conflicting property values and cannot be merged:
	* META-INF/test.properties
	* Property key2 is duplicated 2 times with different values
	""".trimIndent().replace("\n", System.lineSeparator()),
	)
	assertThat(result.output.replace(lineSeparator, "\n")).contains(
	// TODO EXPERIMENT
	"""
	Execution failed for task ':shadowJar'.
	> The following properties files have conflicting property values and cannot be merged:
	* META-INF/test.properties
	* Property key2 is duplicated 2 times with different values
	""".trimIndent(),
	)

[Goooler]

assertThat(result.output.replace(lineSeparator, "\n")) would be better.

[Goooler]

b483f1b