Apply suggestions from code review

Co-authored-by: Chris Smowton <smowton@github.com>

java/ql/lib/semmle/code/java/JDK.qll

@@ -52,9 +52,9 @@ class StringPartialMatchMethod extends Method {
    * The index of the parameter that is being matched against.
    */
   int getMatchParameterIndex() {
-    if not this.hasName("regionMatches")
+    if this.hasName("regionMatches")
-    then result = 0
+    then this.getParameterType(result) instanceof TypeString
-    else this.getParameterType(result) instanceof TypeString
+    else result = 0
   }
 }
 

java/ql/lib/semmle/code/java/environment/SystemProperty.qll

@@ -2,7 +2,7 @@ import java
 private import semmle.code.java.frameworks.apache.Lang
 
 /**
- * Gets Expr that return the value of `propertyName` from `System.getProperty()`.
+ * Gets an expression that retrieves the value of `propertyName` from `System.getProperty()`.
  */
 Expr getSystemProperty(string propertyName) {
   result = getSystemPropertyFromSystem(propertyName) or

java/ql/lib/semmle/code/java/os/OSCheck.qll

@@ -37,7 +37,7 @@ abstract class IsUnixGuard extends Guard { }
 abstract class IsAnyUnixGuard extends Guard { }
 
 /**
- * Holds when the MethodAccess is a call to check the current OS using either the upper case `osUpperCase` or lower case `osLowerCase` string constants.
+ * Holds when `ma` compares the current OS against the string constant `osString`.
  */
 bindingset[osString]
 private predicate isOsFromSystemProp(MethodAccess ma, string osString) {

java/ql/src/Security/CWE/CWE-200/TempDirLocalInformationDisclosure.ql

@@ -104,7 +104,7 @@ private class FileCreateTempFileSink extends FileCreationSink {
 }
 
 /**
- * A guard that checks whether or not the the program is running on the Windows OS.
+ * A guard that holds when the program is definitely running under some version of Windows.
  */
 abstract private class WindowsOsBarrierGuard extends DataFlow::BarrierGuard { }